cmake single file build issues

[Manuel Breugelmans]

This is does not work as expected, see 
https://bugs.kde.org/show_bug.cgi?id=175994

There's a couple more subtle issues with this code.
1/ Now you can do README -> compile and it will try to run `make README.o'
2/ The deletion code (m_deleteWhenDone cmakebuilder.cpp:91;111) is not safe. 
It deletes a ProjectTargetItem in the event loop, the same item that is 
exposed through the built(ProjectBaseItem*) signals. So anyone accessing this 
is fooked.

I think all 3 problems could be fixed with a 'FileTarget' in the project model.


Manuel