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.