Starting improve bidirectional integrator.
Separate class declaration code to bdpt.h header file for cleanup code.
Try to add news parameters:
    - maxPathLength
    - minPathLength
Comment unused lines on color.h
Add defines for MinGW32 compilers in y_alloc.h
Small mismatch typo on BDPT_H guard
Add 'do_lightImage' variable for test.
Indent some license text.
Added outputFile option to yafaray-xml
Merge pull request #11 from rubdos/outputfile

Added outputFile option to yafaray-xml
Review code from 'rubdos' patch:
    - set only the file name, the extension is set with parsing 'f' option
Merge remote-tracking branch 'remotes/origin/bidirectional_cleanup'

Conflicts:
	include/yafray_constants.h
	src/integrators/bidirpath.cc
Merge branch 'master' into release_candidate

Conflicts:
	src/xml_loader/xml-loader.cc