Blender Git Loki

Keymap: continued testing/development

After testing in the studio and extending the event system for
drag events, we've agreed on adjustments to the new keymap,
see: T55162

- Tab: Edit-mode toggle.
- Tab + Cursor Drag: mode switching pie menu.
- Accent/Grave: for 3D view pie menu.
- F3: Search
- 1..3, Shift-1..3: Edit mesh vertex/edge/face toggle.

Other minor changes were made, however they aren't part of the design.

- Ctrl-Shift-S: Image editor Save-As (was F3)
- Ctrl-Alt-R: Repeat history (was F3)