Blender Git Loki

Knife: Added support for multi-object edit mode

Now you can create cuts on all objects in multi object edit mode.
- If a cut is started on a given object it can interact with that same object.
- The current object to be cut is switched based on the nearest edge to the mouse cursor, only when the tool mode is idle.
- When a cut is started in empty space it will interact with the last object the mouse was nearest before the cut was started.

Further improvements could include starting a cut in empty space interacting with the current object the mouse is nearest and allocating BMBVH's for each object on tool init instead of every time an object switch occurs.