exclude CreatePidFile() function on WIN32 as it is unused
Bitcoin-Qt: save and restore position of debug window

- move the code for saving and restoring window positions from BitcoinGUI
  to GUIUtil, make it more generic and also use it for saving/restoring
  debug window positions
fix string in intro.cpp, which is untranslatable on Transifex

- seems the code tags in the original string cause errors, when using the
  Transifex site for translation
Merge pull request #2865 from Diapolo/fix_intro_translation

fix string in intro.cpp, which is untranslatable on Transifex
Merge pull request #2827 from Diapolo/rpccon_winpos

Bitcoin-Qt: save and restore position of debug window
Merge pull request #2855 from Diapolo/guard_CreatePidFile

exclude CreatePidFile() function on WIN32 as it is unused