... in preparation for 0.13

Adds 127.0.0.1:9050 for the .onion proxy if we can succesfully connect
to the control port.

Natural followup to creating hidden services automatically.

- OSX —> OS X
- XCode —> Xcode
- github —> GitHub
- homebrew —> Homebrew
- gitian —> Gitian
- Other miscellaneous obvious spelling fixes and whitespace removal

Mention now allowed sequence of pushdatas in OP_RETURN outputs in
release notes.

Signed-off-by: Johnathan Corgan <johnathan@corganlabs.com>

Assume that when a wallet transaction has a valid block hash and transaction position
in it, the transaction is actually there. We're already trusting wallet data in a
much more fundamental way anyway.

To prevent backward compatibility issues, a new record is used for storing the
block locator in the wallet. Old wallets will see a wallet file synchronized up
to the genesis block, and rescan automatically.

It's unclear if people are using this and if it's worth maintaining.

These changes decode valid SIGHASH types on signatures in assembly (asm) representations of scriptSig scripts.
This squashed commit incorporates substantial helpful feedback from jtimon, laanwj, and sipa.

Add a section "low level RPC API changes" so that the changes with
regard to error codes can be added later.

... in preparation for 0.12

Add information about further notable changes:

- Big endian support
- Memory usage optimization
- Disable wallet transaction broadcast
- Stream isolation for Tor

I dropped mention of libgmp that I had in my first draft because
it looks like we'll be able to get that out prior to release.

Start the RPC server before doing all the (expensive) startup
initialisations like loading the block index.  Until the node is ready,
return all calls immediately with a new error signalling "in warmup"
with an appropriate status message (similar to the init message).

This is useful for RPC clients to know that the server is there (e. g.,
they don't have to start it) but not yet available.  It is used in
Namecoin and Huntercoin already for some time, and there exists a UI
hooked onto the RPC interface that actively uses this to its advantage.

This reverts commit 9fa53dd3.

This reverts commit 7a19efe0.

The wallet now uses the mempool fee estimator with a new
command-line option: -txconfirmtarget (default: 1) instead
of using hard-coded fees or priorities.

A new bitcoind that hasn't seen enough transactions to estimate
will fall back to the old hard-coded minimum priority or
transaction fee.

-paytxfee option overrides -txconfirmtarget.

Relaying and mining code isn't changed.

For Qt, the coin control dialog now uses priority estimates to
label transaction priority (instead of hard-coded constants);
unspent outputs were consistently labeled with a much higher
priority than is justified by the free transactions actually
being accepted into blocks.

I did not implement any GUI for setting -txconfirmtarget; I would
suggest getting rid of the "Pay transaction fee" GUI and replace
it with either "target number of confirmations" or maybe
a "faster confirmation <--> lower fee" slider or select box.