by caching results and storing them in a hash the results should
flow faster, a limit should probably be set on this but for now
there isn't. exists() and realPath() now cannot be called without
object!
for compatibilty reasons automoc4 support is not removed but it
shall be in the future. automoc4 has not been maintained for a
while (last commit is from 2011) and the stable release is from
2009.
CMake version >= 2.8.6 provides the functionality for mocking so
I see no reason to not make use of it.
