Blender Git Loki

Userpreferences Panel (for the 3DView)

This is an attempt to improve the User preferences panel for the 3DView. I made 2 changes:

- I reordered the sequence of properties by grouping them into more logical groups as it made sense to me. Please indicate where to rearrange the order if necessary.

- Then i added some changes in the code to get the groups better arranged visually. I am pretty sure that this can be done much better, more clever, more generic, whatever. This is just what i could figure out on my own so far.

Reviewers: aligorith, sergey, gaiaclary

Subscribers: sergey

Projects: #user_interface

Maniphest Tasks: T47295

Differential Revision: https://developer.blender.org/D1757