Initial CMake port

If this interests you, I'll add more on this. I could look into building on Windows and Mac. Right now it's only for Linux (mostly Deb and Ubuntu) and all should work.
Don't know if Android is possible.

It can be used side by side with qmake and the CMakeList.txt can be imported in QtCreator.

Use with:
$ mkdir build && cd build
$ cmake -DGUI_800x480:bool=true
$ make

You can just launch from the build dir:
$ ./pokerth

You can build 800x640 with:
$ mkdir build && cd build
$ cmake -DGUI_800x480:bool=true ../
$ make

You can also create a deb package with this:
$ mkdir build && cd build
$ cmake -DCPACK_GENERATOR:string=DEB ../
$ make
$ make package