Blender Git Loki

- modifier UI update (aka, find the modifier buttons!!)
- moved back to editing buttons, where life is now cramped... switched
to constraint style foldout panes, still a WIP. In particular not
sure what buttons should be in header (and if current toggles stay
in header if they should also be in an expanded pane). Also need
new icons for move up/move down (and drag and drop would of course
be nice). Finally current plane is to make it so modifiers will
expand out in modifier pane for horizontal orientations instead of
just going down down down to goblin town.
- added error field to modifiers that is displayed in UI, need to have
some way for modifiers to return errors back to interface (esp. important
for python)
- tweaked cage determination and handling, currently the editmode cage
is determined by last modifier with OnCage set that is preceeded completely
by modifiers that support mapping or are disabled in editmode. it is
kinda confusing, but the interface only lets you toggle OnCage for modifiers
that support it - it just might not be clear all the time why you can't
toggle a certain modifier OnCage.
- update displistmesh_copy to only copy edges if non-NULL

There is a display bug that already existed but is more obvious with
new modifiers where parts of the pane get drawn in a different area
after toggling editmode. It has to do with drawing parts of the interface
using GL instead of 100% buttons. I try to keep my grubby little toes
out of the interface code so this can wait for Ton to return.