No major functionality changes.

Tried to order items in order of importance.
Also all perspectives now have their own shortcuts.

Both on the backend (replaced with DEFAULT view) and on the front end (removing UI menu items).

There were two separate actions for the simulation view, leading to
strange behaviour when it was selected.

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>

Reworked the styling UI. Now there are 4 options: light, dark, custom_light, and custom_dark. Things don't quite work right, but the proof-of-concept is done.

Changes for the new "View" navigation, and fixes to get most of the dockwidgets working with the new view system

Addressed issue #26. Select System, Plugins and System are disabled when neccessary. Removed style-outdoor-dark.css. Moved the other two .css files and Vera.ttf into files/styles.