adapt stake miner to new protocol
adapt GetStakeWeight() to new protocol

Conflicts:

	src/rpcmining.cpp
	src/wallet.h
adapt GetPoSKernelPS() to new protocol

Conflicts:

	src/rpcblockchain.cpp
new block timestamp limits

past: time of last block
future: +15 seconds

Conflicts:

	src/main.cpp
new stake protocol

Conflicts:

	src/main.cpp
adapt GetStakeWeight() to new protocol

Conflicts:

	src/wallet.cpp
	src/wallet.h
check block timestamp earlier
remove unneeded code

Conflicts:

	src/miner.cpp
	src/qt/bitcoingui.cpp
	src/wallet.cpp