Added Help module.
Checked in PythonCore.prj.hqx (which had somehow slipped through until
now)

unfortunately, this turned out to be too difficult.

Plugins.prj now builds all plugin modules, and all the
interdependencies between the projects are correct. One exception:
plugins don't attempt to build PythonCore (PythonFAT and PythonApplet do).

projects unified (as much as possible: PythonCore is still separate).