Used for internal apps as well as for plugins. The pluginpart is
currently missing, in fact that the main OpenSlides part is more
important. Apps can give their models and mainmenu entries.
Routes are not enabled, because the routes have to be static for webpack
to build the bundles. If we want to keep lazy loading, I see no
possibility to encapsulate the routes from the site-routing module.
Restructure the titles for motion, motion-block, assignment and topic.
Less possibilities for more clear code. Added mote base models enabling
functionalities of projection and being a content object for items
