Blender Git Loki

Start of revamped design (#2) - New node type enum defines

This commit marks the start of the second attempt at building a new
depsgraph system for Blender. It still uses the base depsgraph types
from the first attempt, but this time, the node types we've chosen to
sit on top of these (for representing the necessary semantic concepts)
have been chosen to be more in line with the requirements we face in
terms of how exactly we're going to be able to use this for evaluating
stuff.

Support for Shapekeys

Pass down Scene pointer instead of scene node

Scene pointer is used more directly more often, while the node
we can easily fetch if/when we need it

Ported over graph building code for a few types

* Curve
* Metaball
* Camera

More blocking out of stuff...

Initial conversion of code for building parenting relationships

Copying over skeleton logic for object parenting

Cleanup

Simplify driver building code using DEG_get_node_from_rna_path()

Expand convenience method used by driver graph building into a useful querying API call

DEG_get_node_from_rna_path()

Renaming relationships types to be more consistent with the rest of the API

Add new relation type for tagging relationships used for driver target links

Fleshing out code to add drivers to depsgraph

This is still quite crude, and starts to show the flavour of how the graph
will need to be constructed. After fleshing out a few more bits like this
we can review the design with greater clarity.

Start of code for adding AnimData (animation + drivers) to depsgraph

Graph Building - Stub for object parents

Graph Building - Stub for materials

Graph Building - Move ob typechecks inside check for whether data exists

Graph Building for Objects - Assorted WIP Tweaks * Moved Constraint and Modifier loops inside checks for existance of stacks * Moved Ob AnimData step to end of object building, so that drivers for bones will be added to the bones as appropriate once they've been created/added to the graph, instead drivers being created to fake/dummy data in the meantime

Add note for what needs review re-inner node linkage

Sectioning notes...