Cmake overhaul

This pull request contains a major overhaul of the CMakeLists.txt structure.
The major changes are:
 * use automoc instead of manually declaring lists of header files;
 * moved Qt4 detection into main CMakeLists.txt
 * properly define CMAKE_INSTALL_PREFIX and use it when needed
 * Create a proper application bundle under OSX
 * Added comments

Some header files were not referenced directly in any cpp file so i had to create dummy cpp files for automoc to handle them correctly.
This change has been tested on:
 * Osx 10.9 Mavericks / clang (XCode 5.1)
 * Slackware-current / g++ (gcc 4.8.2)
 * Windows Xp / MinGW (gcc 4.8.1)

Some changes are still needed to correctly place resource files in the OSX's Application bundle / Windows's release directory, but this pull request is already big enough to discourage me into adding more mess in it.
Does cmake require tab characters? This is really minor but I'd prefer spaces