Added missing SGUI_ prefix to widget change flags

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Moved window_set_vsync and window_get_platform_data

 - Implemented as callbacks in window structure
 - May deviate in window implementations
 - Fewer direct calls into backend

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Revised full-auto-build-and-package script

 - CMakeLists.txt no longer contains doxygen generation and include
   directory generation
 - cleaned Doxyfile
 - removed pack.sh from build directory
 - added package.sh
    - runs all builds
    - generates binary packages for all platforms
    - generates source package
    - generates sdk package with headers and docs

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Updated build system and OOP documentation (HTML manual)

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>