Core system now has a version number and proper output for it; also, restructured main.cpp a bit
Remove unloaded plugins from the index after deleting their instances

Having the old plugin instance references still in the ''m_lstLoadedPlugins'' list results in segmentation faults due to the core system still trying to access their ''cycle()'' value.
Default reaction to failed plugin loading is to invalidate startup altogether

This option can be customized on the config file.
Updated package.xml
Fixed package.xml and added a forgotten '')'' to version output