Split media_resources table

Squashed commit of the following:

commit 5171248be6dcc4eb142bb327200744555d6160e1
Author: Thomas Schank <DrTom@schank.ch>
Date:   Mon Nov 3 10:53:59 2014 +0100

    modified:   doc/diagrams/Schema_vision.graffle

commit e07f0f76fc2d936690f10f00893b9e4d7cd6738e
Author: Thomas Schank <DrTom@schank.ch>
Date:   Mon Nov 3 10:36:33 2014 +0100

    Remove settings from media_resources

commit ee18f8f553e660a6fa3eb154c96f8cc6ad272568
Author: Thomas Schank <DrTom@schank.ch>
Date:   Mon Nov 3 10:09:23 2014 +0100

    Migrate Arcs

commit 2940380adc6fa6f98cc6c5c2d1aa46c54a296f7d
Author: Thomas Schank <DrTom@schank.ch>
Date:   Mon Nov 3 08:35:39 2014 +0100

    Add and migrate filter_sets

commit 335894ca1067137940b3ec7316babd3343939b39
Author: Thomas Schank <DrTom@schank.ch>
Date:   Fri Oct 31 09:36:21 2014 +0100

    Create media_entries table; create rows; repoint media_file fkey

commit 6392afa71d3065c46a50774a5f0feaf696ce2fe8
Author: Thomas Schank <DrTom@schank.ch>
Date:   Fri Oct 31 07:45:20 2014 +0100

    Migrate Types of media_resources_table