Blender Git Loki

Fancy procedural icons for Keyframe Types

The new "default keyframe type" dropdown on the timeline header
(and also the "Keyframe Type" operator/properties in other places)
now has procedurally generated icons which reflect what that keyframe
type will look like when rendered in the Dope Sheet.

This was achieved using the ancient "VICON" (vector icon) stuff
that's lurking around in the dark parts of UI code. From memory,
the only other things that use (or used to use) this stuff included
some of the triangle icons for some dropdown buttons, or something
like that.

Notes:
* Theme colour changes are reflected immediately by these icons.
This is possible because they are all drawn procedurally
* These icons scale with the DPI setting. I manually guessed the size of
these icons. They can be adjusted further if needed.
* I've documented the steps for adding voodoo icons like this on the wiki
(http://wiki.blender.org/index.php/Dev:2.7/Source/Checklists/Vector_Icon)
* It's true that the rendering of these keyframes doesn't quite fit the rest
of the icons in the UI. However, since we're just leveraging the standard
keyframe drawing methods (to avoid discreptancies between the two), we'll
leave it as such for now. Maybe later we can consider blending in a bit of
the glossy keyframe icons in the Icon Sheet?