Add new parameters to Bidirectional integrator for test.
Merge branch 'improve_bidir' of https://github.com/TheBounty/Blender-Exporter into improve_bidir

Conflicts:
	io/yaf_integrator.py
	prop/yaf_scene.py
	ui/properties_yaf_integrator.py
Jump EXR libraries to 2.1 version for GCC 4.8.1
Solved some issues after merge.
Update 'bidirectional' name from 'Bidirectional'