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
Update README.md

Added two modifications to make the descriptions more clear.
[Qt] Fix thin space in URI
Merge pull request #4563

027dcdc [Qt] Fix thin space in URI (Cozz Lovan)
qt: Move SplashFinished to after ClientModel/WalletModel creation

With a large wallet there was a noticable gap between hiding of the
splash and showing the main window.
Revert "Remove signal DoubleSpendDetected, use function"

This reverts commit 0da6b3fd187da3aa810aaa584d8bd197ad4fa2b9.
Revert "Check signatures before respend relay"

This reverts commit 88dd3598d22197a22565e524cecdc08107cf76ac.
Revert "Formatting, spelling, comment fixes."

This reverts commit 7a19efe04069d9a1e251cdc94b25184f76d9d901.