afaik, this was a bizarre hack to make the install target work, so fix
it properly instead.

Reviewed-By: Oswald Buddenhagen

On Windows, for unknown reasons, qhelpgenerator.exe sometimes will
not generate the documentation if run directly from nmake.
Running it through an intermediate cmd seems to work.
So, do that.

Reviewed-by: Daniel Molkentin

This makes it easier to open them from inside qt creator.

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.

Details: Moving files so that the local layout corresponds to the layout pushed by make install.
Adjust Make target, modify the resource path of the loader to find the resources in the
right place. All pathes are still looked up relative to binaryPath(), libs are found via
relative rpath.

fix doc target. this does still not solve the problem that qdoc has to be build in release mode if you use windows.

It assumed qhelpgenerator was in the path, though this isn't necessarily
the case. Use the absolute directory instead.

RevBy:    - bjørn