[CMake] Cmake with Eclipse

[wedekind]

Hi Alex,

> There is a new class cmExternalMakefileProjectGenerator, which can be
> subclassed and be used to create project files for your prefered IDE.

This is really cool! I have implemented such a makefile-based generator with
additional IDE-files and it was quite annoying to set it up. Basically
because you could not just reuse an existing makefile-generator and simply
add the code to generate the IDE-files.

I'll give it a try.

Cheers!

Marco