Blender Git Loki

Refactor: Copy/Paste values from/to UI

Previously copy and paste was handled within the same function using a mode switch, which is quite ugly in most cases.
This patch separates the function into two and splits up those in even smaller functions to increase maintainability.

Finally one new feature was added: You can copy from disabled fields now. (requested by hjalti)

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3738