Former-commit-id: 66f0baa03b21f972e974b89cd89890568043f2a7

Passes tests:

```
$ ./bitcoin-qt 'bitcoin:?r=http://www.example.com/'
.. fixed the original problem - this launches mainnet.

$ ./bitcoin-qt 'bitcoin:mngeNQbTKnmaMbx8EXCYdwUbnt9JJD52cC'
.. launches testnet

$ ./bitcoin-qt -testnet 'bitcoin:1NXXeQRyMFFFRfyUix2o7mk1vhvk2Nxp78'
.. sanity check - launches mainnet.
```

Fixes #4355. Closes #4411.

Rebased-From: dd49e92f

- as a proxy set via GUI can be overridden via -proxy, directly query the
  core to get active proxy
- give a warning, if active proxy is not SOCKS5 (needs to be SOCKS5 for
  the Qt networking code to work)
- also remove an obsolete connect() call from optionsdialog.cpp and a
  reference to Bitcoin-Qt (now just GUI)

Fixes at least #3478.

Splits and documents the phases:
1. Parse command-line options. These take precedence over anything else.
2. Basic Qt initialization (not dependent on parameters or configuration)
3. Application identification
4. Initialization of translations
5. Now that settings and translations are available, ask user for data directory
6. Determine availability of data directory and parse bitcoin.conf
7. URI IPC sending
8. Main GUI initialization

Splits command line parsing logic from ipcSendCommandLine into
ipcParseCommandLine, as isTestNet() can only be overridden in the early
stages before choosing a data directory. Sending however needs to happen
after choosing a data directory.

- important for the open URI dialog to give users feedback
  when a file is invalid etc.

- make eventFilter() private and pass events on to QObject::eventFilter()
  instead of just returning false
- re-work paymentservertest.cpp to correctly handle the event test
  after the above change (rewrite test_main to allow usage of
  QCoreApplication:: in the tests)
- delete socket when we were unable to connect in ipcSendCommandLine()
- show a message to the user if we fail to start-up (instead of just a
  debug.log entry)
- misc small comment changes

BIP 72 was changed to save six bytes in bitcoin: URIs.

- remove explicit init of netManager as this is done in the constructor
  anyway
- move initNetManager() call to uiReady(), which removes an assert() and
  allows us to use message() in initNetManager() (currently unused but
  could be necessary because of proxy related messages)
- make initNetManager() private
- update paymentservertests.cpp

Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.

Closes #839

- use a QStringList to store valid addresses and format them for GUI and
  debug.log usage via .join()

- as one this pulls main purpose is to change a payment request to
  be displayed as a single sendcoins entry

- this shows insecure (unsecured) payment requests in a new yellowish
  colored UI (based on the secure payment request UI) instead of our
  normal payment UI
- allows us to receive paymentACK messages for insecure payment requests
- allows us to handle expirations for insecure payment request
- changed walletmodel, so that all types of payment requests don't touch
  the addressbook

- re-work -debug help message text
- make -debug log every debugging information again (even all categories)
- remove unneeded fDebug checks in front of LogPrint()/qDebug(), as that
  check is done in LogPrintf() when category is != NULL (true for all
  LogPrint() calls
- remove fDebug ONLY in code which is NOT performance-critical
- harmonize addrman category name
- deprecate -debugnet usage, should be used via -debug=net and remove the
  corresponding global

- add new slot handlePaymentACK() to paymentserver, which handles
  paymentACK messages (currently we just display them)
- make paymentACK message a modal information dialog
- change some QObject::tr() to just tr()
- clarify the processPaymentRequest() error, when IsDust()
- small string change to prevent a tripple + usage with QString

- rename reportError() into message() to be in line with our default
  message() signal/slot naming (and can be used for all types of messages)
- rename some QStrings to not collide with message() function
- add a missing message for malformed URIs that IS also used in BitcoinGUI
- fix / extend some comments and misc style fixes

- make processPaymentRequest() use our own HTML-escaping function from
  GUIUtil
- make string "application/bitcoin-payment" a constant (below similar
  constant strings in the .cpp file)

- rename URL into URI in paymentserver where correct
- add some missing Qt-coding-stuff in paymentserver
- change QSpinBox to QLineEdit as base for BitcoinAmountField in .ui files
  (as this is the result when converting the BAF back into base)
- remove some c_str() and replace with QString::fromStdString()
- remove several new-lines
- remove unneeded spaces
- indentation fixes

- removes all usages of PrintDebugStringF from Qt code
- ensure same format for all debug.log messages "functionname : Message"

- extend PaymentServer with setOptionsModel() and rework initNetManager()
  to make use of that
- fix all other places in the code to use display unit from options and no
  hard-coded unit

Suggestion from BitPay: set an Accept: HTTP header when
fetching payment requests / payment ACKs.

With the GUI password fix this was always false.

Add support for a Payment Protocol to Bitcoin-Qt.

Payment messages are protocol-buffer encoded and communicated over
http(s), so this adds a dependency on the Google protocol buffer
library, and requires Qt with OpenSSL support.

Replace the loop macro with while (true). The #define caused
problems for Qt.

- move all QApplication includes to top of included Qt headers
- undef our loop macro where it would cause compilation errors otherwise

This commit squashes all the changes in the Qt5 branch
relative to master.

Backward compatibility with Qt4 is retained.

Original authors:

- Philip Kaufmann <phil.kaufmann@t-online.de>
- Jonas Schnelli <jonas.schnelli@include7.ch>

- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility

Switch to using Qt's QLocalServer/QLocalSocket to handle bitcoin
payment links (bitcoin:... URIs)

Reason for switch: the boost::interprocess mechanism seemed flaky,
and doesn't mesh as well with "The Qt Way"

qtipcserver.cpp/h is replaced by paymentserver.cpp/h

Click-to-pay now also works on OSX, with a custom Info.plist
that registers Bitcoin-Qt as a handler for bitcoin: URLs and
an event listener on the main QApplication that handles
QFileOpenEvents (Qt translates 'url clicked' AppleEvents into
QFileOpenEvents automagically).