- Force AUTHCOOKIE size to be 32 bytes: This provides protection against
  an attack where a process pretends to be Tor and uses the cookie
  authentication method to nab arbitrary files such as the
  wallet
- torcontrol logging
- fix cookie auth
- add HASHEDPASSWORD auth, fix fd leak when fwrite() fails
- better error reporting when cookie file is not ok
- better init/shutdown flow
- stop advertizing service when disconnected from tor control port
- COOKIE->SAFECOOKIE auth

Starting with Tor version 0.2.7.1 it is possible, through Tor's control socket
API, to create and destroy 'ephemeral' hidden services programmatically.
https://stem.torproject.org/api/control.html#stem.control.Controller.create_ephemeral_hidden_service

This means that if Tor is running (and proper authorization is available),
bitcoin automatically creates a hidden service to listen on, without user
manual configuration. This will positively affect the number of available
.onion nodes.

- When the node is started, connect to Tor through control socket
- Send `ADD_ONION` command
- First time:
    - Make it create a hidden service key
    - Save the key in the data directory for later usage
- Make it redirect port 8333 to the local port 8333 (or whatever port we're listening on).
- Keep control socket connection open for as long node is running. The hidden service will
  (by default) automatically go away when the connection is closed.

7ca73dcf Improving labels for Sent / Received "Bytes" (Jonathan Cross)

e20d9245 [trivial] init: Use defaults MIN_RELAY_TX_FEE & TRANSACTION_MAXFEE (MarcoFalke)
536766c9 [trivial] New DEFAULT_MIN_RELAY_TX_FEE = 1000 (MarcoFalke)
5f46a7d0 transaction_tests: Be more strict checking dust (MarcoFalke)

fd55571f wallet: Expose GUI labels in RPC (Luke Dashjr)

87cbdb8b Globals: Explicit Consensus::Params arg for main: (Jorge Timón)

* Don't allow off-by-one or more
* Make clear dust is coupled with minRelayTxFee
* Check rounding for odd values

9ea7762e Use Pieter's signing subkey instead of his primary key (Matt Corallo)

c53d48a6 BIP70: Chainparams: DRY: Make qt/guiutil.cpp fit BIP70 chain name strings (Jorge Timón)

6dd3a44c translations: Don't translate markdown or force English grammar (MarcoFalke)

2980a185 Fix crash in validateaddress with -disablewallet (Wladimir J. van der Laan)

Fix a null pointer dereference in validateaddress with -disablewallet. Also add a regression testcase.

This commit is signed.

e167af2a [doc] Remove excessive white space (MarcoFalke)
e0eeb672 [trivial] clang-format: Set AlignAfterOpenBracket: false (MarcoFalke)
0af8fe45 devtools: Update README.md (MarcoFalke)

22e78073 Always flush block and undo when switching to new file (Pieter Wuille)

d1c3762a Revert "Revert "Enable policy enforcing GetMedianTimePast as the end point of lock-time constraints"" (Gregory Maxwell)
e4e5334e Restore MedianTimePast for locktime. (Gregory Maxwell)

53238ff0 Clarify what minrelaytxfee does (MarcoFalke)
abd8b768 [qt] Properly display required fee instead of minTxFee (MarcoFalke)

fb9857bf Squashed 'src/leveldb/' changes from 7d41e6f..20ca81f (Pieter Wuille)

Previously, the undo weren't being flushed during a reindex because
fKnown was set to true in FindBlockPos. That is the correct behaviour
for block files as they aren't being touched, but undo files are
touched.

This changes the behaviour to always flush when switching to a new file
(even for block files, though that isn't really necessary).

20ca81f Merge pull request #9
7aa105e leveldb: Win32WritableFile without memory mapping

git-subtree-dir: src/leveldb
git-subtree-split: 20ca81f08fb7fa108923a091668e447dcf5c6b9d

The labels for Sent & Received data in the "Peers" debug panel should not be defined as "Bytes" because the units (B, KB, MB) appear after the number.  I decided to simply use "Sent" and "Received" (rather than "Data Sent" and "Data Received") because we already have translations for the former:
https://www.transifex.com/bitcoin/bitcoin/viewstrings/#ja/qt-translation-011x/47533089?q=sent
https://www.transifex.com/bitcoin/bitcoin/viewstrings/#ja/qt-translation-011x/47533089?q=received

Demo of changes:

Current UI:
    Bytes Sent      12 KB
    Bytes Received  26 MB

With this pull request:
    Sent       12 KB
    Received   26 MB

dbacc69b build: If both Qt4 and Qt5 are installed, use Qt5 (Wladimir J. van der Laan)

If both Qt4 and Qt5 development headers are installed, use Qt5. Building
against Qt5 should be encouraged as that is where active development
happens.

As a side effect, the qt user will see "test" instead of "testnet"

268b79ef [qt] rpcconsole: Scale monospace font to 95% (MarcoFalke)
28313b83 [qt] Use fixed pitch font for the rpc console (MarcoFalke)

6342a488 Init: Use DEFAULT_TRANSACTION_MINFEE in help message (MarcoFalke)
a9c73a13 [wallet] Add comments for doxygen (MarcoFalke)
6b0e622c [wallet] Refactor to use new MIN_CHANGE (MarcoFalke)

de0499d3 Fix ZMQ Notification initialization and shutdown (João Barbosa)

35bb3814 build: Improve build instructions (Wladimir J. van der Laan)

- Add package instructions for Ubuntu 15.10
- Clarify BerkeleyDB/wallet situation for unix
- Add basic build instructions for Windows (closes #1401)

a6efc019 Bugfix: Omit wallet-related options from -help when wallet is disabled (Luke Dashjr)
5f9260f4 Bugfix: If genproclimit is omitted to RPC setgenerate, don't change it; also show correct default in getmininginfo (Luke Dashjr)
420a82f1 Bugfix: Describe dblogsize option correctly (it refers to the wallet database, not memory pool) (Luke Dashjr)
caa3d42f Bugfix: RPC: blockchain: Display correct defaults in help for verifychain method (Luke Dashjr)