this is based on patches from axasia, which are in turn an almost
literal copy from qt.

Details:  Creator on Linux works now in two modes:
          1) out of the build dir (shadow builds to be tested)
          2) make INSTALL_ROOT=/prefix install

Details:  Make install works now, we just have to agree on layout
details and check for mac compatibility.

Also, plugins will carry no version in their filename anymore starting with
this commit. Versioning happens in the creators pluginloader using the pluginspec file.

RevBy:    - bjørn

RevBy:    con