get rid of mapProofOfStake
Revert "add menu item About BlackCoin card"

This reverts commit d9f4741b77ceed519ade3958b45839e15109540a.
update readme
check staking is disabled before allowing to use accounting api
fix debug message
add stake mod checkpoint
clean up extern declarations
update checkpoint span
reject unknown block version
Fix importprivkey / rescan

Conflicts:
	src/rpcdump.cpp
importprivkey: Don't throw error in case a key is already there
Allow the default key to be unavailable

This solves the issue where no default key can be added after -salvagewallet.

Conflicts:
	src/main.cpp
	src/wallet.cpp
prepare for changing block hash
complete check for low S in signatures
fix unconfirmed balance if wallet contains conflicted transactions
Squashed 'src/leveldb/' changes from 9094c7f..7924331

42dcc7e Merge upstream LevelDB 1.17.
e353fbc Release LevelDB 1.17
269fc6c Release LevelDB 1.16
REVERT: 9094c7f Temporarily revert to writing .sst files instead of .ldb

git-subtree-dir: src/leveldb
git-subtree-split: 79243314e40ac31d79c68e5658a1d6a64800d50b
update build docs
follow 10-confirms recommendation in coin selection
update build docs
json_spirit: #include <stdint.h>