I have written a CMake build file in an effort to migrate to a more cross- platform build system.

Currently, it performs the same tasks as the Makefile.orig in SVN plus detection of the GTK and SDL paths.

I have tried to compile the software under Windows with this, but there are some particulars with main.cpp and GTK that need to be ironed out first. I'll open separate issues for these.

The other issues have hopefully been dealt with enough to proceed with a cmake system. Let me know if you need anything.

There, a modified CMakeLists.txt is now in at rev 14. Thanks!