Build from 2017-01-08 : Advanced Commands

So here is a smaller update after the two big on paints.
This time I focused more and advanced commands if you want to be more efficient check them out.

[CHANGELOG]
* Added Pick block Command (default is middle mouse)
* Added Pick Color Command (default is CTRL - middle mouse)
* Can build extension in 2D with CTRL pressed twice
* Repeat command : CTRL-R to repeat last build action (usefull for extension)
* Corner block build is easier.
* Added Undo / Redo function CTRL-Z CTRL-Y (not working with delete extension)
* Armature Tri block.

Check the vid for a demo of the commands.