[cmake][bugfix] Trigger reconfiguration on meta ini change
This is an extremely important for the meta ini format to be usable in practice. The technical solution is a hack, which is very elegant nevertheless. I found it on the cmake mailing list:
http://www.cmake.org/pipermail/cmake/2013-October/055987.html
It uses the semantics of configure_file, which do automatically trigger reconfiguration. For us reconfiguration involves reexpansion.
This fixxes #40 (closed).