The layer names are then used in creating the custom rig layer UI.  This is
useful for users that do not want to--or do not have the knowledge to--edit
the generated python script by hand.  It is also handy even for more advanced
users when regerating the rig over and over (which over-writes the script
and any hand-made edits).

Also misc bug fixes in some of the rig types.

This allows IK arms and legs to still function properly even when they
start with an entirely straight chain.

This rig replaces the old spine rig, and has a super-set of the old spine's
features.  The main new features are:
1. A separate over-all control for translation.  Due to the pivot slide
   feature of the spine, it didn't really make sense to have one of the
   spine bones be the control for translation, so I broke that out
   into a separate control.  This control also acts as a root of the
   spine in general, including for scaling and rotation.  If you
   want to grab the entire spine as one unit, this is how to do it.
2. The spine can now have more than two control bones.  The rigger
   can specify an arbitrary number of the spine bones to be
   turned into controls upon rig generation.
   Controls that are not at the end points of the spine
   are optionally (via an animatable switch) auto-rotated by the
   the end point controls, so animators can ignore them when they
   do not require that level of control.

- h3d: replace unfinvviewmat with gl_ModelViewMatrixInverse

-Fixed Blender_export issue. Thanks to Perfection Cat providing the fix.

* Modified the "Add X,Y,Z Function Surface" part:
* Changed how wrapping is done to avoid generating unnecessary vertices and make the result more intuitive.
* Added helper functions the results of which can be used in x(u,v), y(u,v), z(u,v).
* The script can now close the ends of an U-wrapped surface.
* It's now possible to create multiple objects with one set of formulae.

-fixed the bug when two or more objects dosen't have materials.

Update the script to work with latest trunk. Still some bugs when "remember position" = On, but much better than before.

Added export of only renderable objects via outliner hide_render property and active layers. Also thanks to all those who helped bringing instances through their designs or advice: Conz, mont29, Campbell.

Render POVRay addon: Now using instances for objects’ data, to avoid having exported hundred times the same mesh/material…
Coded in collaboration with MauriciusRay.

object hierarchy (parent/child) support for X3D export, tested with dupli-groups, scaling, rotations.
keep this optional so exporting without hierarchy is still supported.

- use XML escaping rather then cleaning to for strings