Made plugins work

This makes kparts/kplugins proper use QPluginLoader.
Currently only static plugins are supported (means
tested and work) what means external dynamic loaded
plugins are not a target yet.

With this commit all Calligra plugins (textshape,
pictureshape and variables) and the Words and
Author KPart's are proper registered as static
QPluginLoader plugins. It works and we can query
instances from the factories now at runtime.

Next step is to proper query such instances, inject
them the proper Calligra factory's/registry's and
continue fix bugs/crashers on the way to load and
display ODT documents.