Blender Git Loki

Four-in-one commit:

(NOTE: new include dependency in Render module, might need MSVC update!
It has to include the imbuf/intern/openexr/ directory in search path)

-> New Composite node: "Hue Saturation".
Works like the former 'post process' menu. There's no gamma, brightness or
multiply needed in this node, for that the Curves Node functions better.

-> Enabled Toolbox in Node editor
This now also replaces the SHIFT+A for adding nodes. The nodes are
automatically added to the menus, using the 'class' category from the
type definition.

Current classes are (compositor examples):

Inputs: RenderResult, Image
Outputs: Composite, Viewer
Color Ops: RGB Curves, Mix, Hue Saturation, AlphaOver
Vector Ops: Normal, Vector Curves, Map Value
Filters: Filter, Blur, VectorBlur
Convertors: ColorRamp, RGBtoBW, Separate RGBA, Separate HSVA, Set Alpha
Generators: RGB, Value, Time
Groups: the list of custom defined nodes

-> OpenEXR tile saving support
Created an API for for saving tile-based Images with an unlimited amount
of layers/channels. I've tested it for 'render result' now, with the idea
that this can (optionally) replace the current inserting of tiles in the
main result buffers. Especially with a lot of layers, the used memory for
these buffers can easily go into the 100s of megs.
Two other advantages:
- all 'render result' layers can be saved entirely in a single file, for
later use in compositing, also for animation output.
- on each render, per scene, a unique temp file can be stored, allowing
to re-use these temp files on starting Blender or loading files, showing
the last result of a render command.

The option is currently disabled, needs more work... but I had to commit
this because of the rest of the work I did!

-> Bug fix
The Image node didn't call an execute event when browsing another image.