Port build system to CMake

[CyberTailor]

Rationale:
CMake is the de-facto standard build system for Qt now, also it's more flexible.

Other changes:
ui_extended.h had to be renamed because it conflicts with AUTOUIC.

ArenaTracker.rc file (Windows resources, including icon) needs to be checked for errors.

TODO:

• [ ] Make OpenCV optional
• [ ] Add a flag to bypass premium check