Merge pull request #8 from zhouguangfu/master

Add fixed threshold SRG test with some bugs to be fixed sooner.
modify average contrast
Merge pull request #9 from liuzhaoguo/master

modify average contrast
Delete ACB_image and fixed_region_grow
Merge pull request #10 from liuzhaoguo/master

Delete ACB_image and fixed_region_grow
Merge branch 'master' of github.com:BNUCNL/region-growing-froi

Conflicts:
	algorithm/region_growing.py
Remove RegionGrowing class and rename the FixedThresholdSRG class to SeededRegionGrowing.