Per-peer block download tracking and stalled download detection.

Keep track of which block is being requested (and to be requested) from
each peer, and limit the number of blocks in-flight per peer. In addition,
detect stalled downloads, and disconnect if they persist for too long.

This means blocks are never requested twice, and should eliminate duplicate
downloads during synchronization.
always show syncnode in getpeerinfo (fixes #2717)
Display progress of rescan.
Add progress to initial display of latest block downloaded.
move wallet info stuff to "getwalletinfo" rpc (left original wallet
stuff in getinfo call for backwards compatibility)

add wallet transaction count to getwalletinfo rpc call
replace custom GetFilesize() with boost::filesystem::file_size()
Slightly tweak error when unable to bind port

A slight improvement over 2d2d8fae3d8bc4e82dc631d93c6e19f954bbee04 -- we don't know that it's the daemon, it could be the GUI.
Update the list of threads to the current state.
Remove unused includes of boost lexical_cast

We don't use lexical_cast anywhere, no need to include it.
Merge pull request #3514

f59d8f0 Per-peer block download tracking and stalled download detection. (Pieter Wuille)
doc/build-unix.md  use github flavored md for table
Transifex pull pre-0.9.0rc3/final
Merge pull request #3835

064a690 Transifex pull pre-0.9.0rc3/final (Wladimir J. van der Laan)
Merge pull request #3829

a75cacd doc/build-unix.md  use github flavored md for table (Torstein Husebø)
Merge pull request #3815

5283410 Remove unused includes of boost lexical_cast (Wladimir J. van der Laan)
qt: Remove control characters from ko_KR translation

Last Transifex pull (064a690) introduced a few control characters
into the Korean translation, which sometimes causes the build to fail.

Manually remove these characters for now to get the build working --
they should still be removed at Transifex too.
Merge pull request #3717 from djpnewton/wallet-txcount

add getwalletinfo RPC call with wallet transaction count
Make mining fee policy match relay fee policy.

This resolves a case in which a mismatch could be used to bloat up the
mempool by sending transactions that pay enough fee to relay, but not
to be mined, with the default policies.
Add script test to prove that OP_0 evaluates as the empty vector, rather than [0].
Fix for GetBlockValue() after block 13,440,000

Forces the block reward to zero when right shift in GetBlockValue() is
undefined, after 64 reward halvings (block height 13,440,000).