Discourage fee sniping with nLockTime
Fix IsInitialBlockDownload which was broken by headers first.
[Wallet] Reduce minTxFee for transaction creation to 1000 satoshis
bitcoin-tx: Add the "-txid" option. Also add the hex-encoded transaction to the JSON output as the "hex" property.
Add a locking mechanism to IsInitialBlockDownload to ensure it never goes from false to true.
Qt: new icons

- flat and b/w icons seems to be the new trend
- support for HiDPI/retina
- change icon sizes
- fix assets-attribution.md
- removed unused icons
Check against MANDATORY flags prior to accepting to mempool

Previously transactions were only tested again the
STANDARD_SCRIPT_VERIFY_FLAGS prior to mempool acceptance, so any bugs in
those flags that allowed actually-invalid transactions to pass would
result in allowing invalid transactions into the mempool. Fortunately
there is a second check in CreateNewBlock() that would prevent those
transactions from being mined, resulting in an invalid block, however
this could still be exploited as a DoS attack.
Reset setBlockIndexCandidates once block index db loaded
[Qt] the RPC Console should be a QWidget to make window more independent

- fix issue #5254
init: minor parameter interaction updates

- use __func__ instead of hard-coded function name for logging
- update -discover help message to reflect newly added parameter
  interaction
- use DEFAULT_LISTEN in a parameter interaction check instead a hard coded
  value
Win32: log addresses found in Discover() calls
Win32: change buffer size for gethotsname in Discover()

- 256 byte is the maximum, as per
  http://msdn.microsoft.com/en-us/library/windows/desktop/ms738527%28v=vs.85%29.aspx
Abstract context-dependent block checking from acceptance
CreateNewBlock and miner_tests: Also check generated template is valid by CheckBlockHeader, ContextualCheckBlockHeader, CheckBlock, and ContextualCheckBlock
TestBlockValidity function for CBlock proposals (used by CreateNewBlock)
miner_tests: Disable checkpoints so they don't fail the subsidy-change test
Abstract DecodeHexBlk and BIP22ValidationResult functions out of submitblock
change nSubsidy's type from int64_t to CAmount
Implement BIP 23 Block Proposal
QA RPC tests: Add tests block block proposals