Fixes error
Only remove actualy failed blocks from setBlockIndexValid
Only keep setBlockIndexValid entries that are possible improvements
Reject transactions with excessive numbers of sigops
Add helptexts for -whitelist and rpc prioritisetransaction and switch to bitcoin instead of satoshis
Add a new checkpoint at block 295,000

Block 295,000 seems to meet the criteria of a reasonable timestamp and
no strange transactions. 295,000 is the current block height in the
bootstrap.dat torrent provided by jgarzik.
net: add SetSocketNonBlocking() as OS independent wrapper
additional test for OP_SIZE in script_valid.json
script tests: BOOLAND, BOOLOR decode to integer

unlike other boolean checks, arguments >5 bytes invalidate the script
script tests: values that overflow to 0 are true
script tests: value with trailing 0x00 is true
script test: test case for 5-byte bools
script tests: add tests for CHECKMULTISIG limits
remove an unneded .c_str() in OpenNetworkConnection()
Harmonize importprivkey and importaddress documentation
build: fix broken boost chrono check on some platforms

If clock_gettime is implemented outside of libc (librt in this case), configure
would fail when testing boost. Since clock_gettime is not present on all OSs,
boost only uses it when it can. Check for it in librt and add it to LIBS if
found, but don't fail if it's not (since boost won't be expecting it in this
case).

Also, reverse the link order as necessary for static libs.

Note that it's possible that there are other similar cases for boost, which may
be handled the same way.
gitian: remove unneeded option after last commit
Merge pull request #4571

a7ec027 gitian: remove unneeded option after last commit (Cory Fields)
460b32d build: fix broken boost chrono check on some platforms (Cory Fields)
Bugfix: make CCoinsViewMemPool support pruned entries in underlying cache
qt: Use fixed-point arithmetic in amount spinbox

Fixes various issues and cleans up code

- Fixes issue #4500: Amount widget +/- has floating point rounding artifacts
- Amount box can now be emptied again, without clearing to 0

Also aligns the amount to the right, as in other places.