Blender Git Loki

Huge commit, but not much features... had to shuffle a lot of code around.

Main target was cleanup of editconstraint.c and removal of the ugly
ob->activecon (active constraint channel), which was set by the "Show"
button in the Constraint Panel.
Better is to introduce an 'Active Constraint' itself, which stores in
the Constraint itself. By using this setting, and by checking the active
Bone, the UI can update reliably now. This only shows now in IpoWindow
btw (for constraint ipos). The active Constraint is drawn in the Buttons
with a slightly brighter backdrop. Any action in that Panel selects a
constraint now (even click in backdrop).

So now we have pose channels & constraint channels nicely behaving. Now the
darn Action channels... :)

Further in this commit:

- interface.c: Button ROUNDBOX now does button callback too.
Button NUMSLI didn't do the callback on a click only

- Cleaned up include files in yafray, got annoyed it compiled over all the
time.

- removed unused variables from Constraint struct