Discourage fee sniping with nLockTime
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.
[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
libbitcoinconsensus: Add pkg-config support
Do all block index writes in a batch
Add /opt/local/include/db48 only if it exists.
Move SendMoney() to rpcwallet.cpp.
[Qt] fix missing plural form for a string in sendcoinsdialog

- this was reported on Transifex by pryds (Thank you!)
[Qt] change some strings to reflect name change to Bitcoin Core
[Qt] fix a translation that occurs 2 times but was a little different
Test unexecuted OP_CODESEPARATOR

OP_CODESEPARATOR is an actual executed instruction, not a declarative
thing, so if it's wrapped in an OP_IF it can be turned off.

Using this to implement Rivest's Paywords is left as an exercise for the
reader.
Use RPC_INVALID_PARAMETER instead of RPC_WALLET_ERROR for invalid amount.
No return at the end of void function.
Revised translation process doc
Make several small string fixes in linearize-data.py

- Add a space after the fixed string prepended to file names when input or
  output file changes
- Clarify the error message when the genesis block is not found in the
  hash list (...why do we have this at all?)
Remove genesis block hash from error
Remove coinbase-dependant transactions during reorg.

This still leaves transactions in mempool that are potentially
invalid if the maturity period has been reorged out of, but at
least they're not missing inputs entirely.
Remove txn which are invalidated by coinbase maturity during reorg
Make CTxMemPool::check more thourough by using CheckInputs