Restart-warning for spendZeroConfChange option

According to the options model, a restart is required after changing this option. So let's notify the user about it.
Fix a typo in RPC signrawtransaction help
Merge pull request #4020

71f82bf Restart-warning for spendZeroConfChange option (langerhans)
doc: remove versions from build-unix.md, just refer to release-process.md

No one bothers to keep this up to date.
Better to refer to another file than give wrong information.
Merge pull request #4031

f3f2cb7 doc: remove versions from build-unix.md, just refer to release-process.md (Wladimir J. van der Laan)
Merge pull request #4024

ab64381 Fix a typo in RPC signrawtransaction help (Hector Jusforgues)
tried to merge in sipa's watch-only patch

Conflicts:
	src/rpcserver.cpp
qt: Hide unspendable outputs in coin control
Watchonly balances are shown separately in gui.
Watchonly transactions are marked in transaction history
added watchonly parameter to getbalance and fixed errors in balance calculation.
added watchonly parameter to listaccounts
added watchonly parameter to listtransactions and listsinceblock
Showing 'involvesWatchonly' property for transactions returned by 'listtransactions' and 'listsinceblock'.
It is only appended when the transaction involves a watchonly address.