Add code for custom material nodes from local repository:
    - this is a most primary implementation of  material nodes
    - Add, register and unregister, news "imports" for custom nodes
    - Add "yaf_custom_nodes.py" file contain new definitions for nodes.
Merge branch 'master' into custom_nodes
Beginning re-write some UI for:
   - add render passes
   - integrate new SSS material
   - add 'SSS' presets
   - add 'material' presets
Start re-writing properties..
   - use 'class' instead 'def' for create own sub-classes
   - use 'PointerProperty' for access to these sub-classes
   - use separate 'enumerate' lists for EnumProperty 'props'
   - make more 'cleaned' code..
Update old 'AddPresetsBase' code..
   - start 'work in progress' code for save presets in arbitrary folder
Add support for new 'material' and 'render' presets
Update some properties..
   - now is not need use 'autothreads':
      - change 'threads' value to '0' for use all threads
   - move 'gamma out' to new Blender 'Color management' panel
Change some old names to TheBounty fork..
Merge branch 'to_bounty' into merge_SSS

Conflicts:
	__init__.py
	io/yaf_export.py
	io/yaf_integrator.py
	io/yaf_light.py
	io/yaf_material.py
	io/yaf_scene.py
	io/yaf_world.py
	ot/yafaray_operators.py
	ot/yafaray_presets.py
	prop/yaf_material.py
	prop/yaf_scene.py
	ui/properties_yaf_general_settings.py
	ui/properties_yaf_integrator.py
	ui/properties_yaf_material.py
	ui/properties_yaf_render.py
	ui/properties_yaf_texture.py