translation update 2013-06-25

- updates bitcoinstrings.cpp and bitcoin_en.ts so new translations can be
  made on Transifex
Merge pull request #2209 from CodeShark/WalletRegistrationLocks

Wallet registration locks in main.cpp + UnregisterAllWallet() function
Merge pull request #2174 from CodeShark/sync_macro_clarification

Added comments to sync.h to make it easier to understand the macros
Merge pull request #2793 from Diapolo/translations

translation update 2013-06-25
Fix build date for from-tarball builds
Merge pull request #2803 from sipa/tarversion

Fix build date for from-tarball builds
Added CWalletManager class to support loading of multiple wallets.