Say hello (again) to CMake!

After struggling way too long with qmake and its lack of features and documentation,
CMake is back in our sources. This is the first sorta working version of our new
shiny CMake-based build system. It seems to work for dynamic builds on Linux at least...
More stuff is to come to allow selection of Qt sources, and we probably need to add a lot
of stuff for Windows and Mac builds. Anyway, this is a start!