Merge pull request #5 from liuzhaoguo/master

add 4d region growing
add something
Merge branch 'master' of github.com:BNUCNL/region-growing-froi
Add seeds class and RegionOptimizer class, and make the grow function of the FixedThresholdSRG look more clean.
Merge pull request #6 from zhouguangfu/master

Add seeds class and RegionOptimizer class, and make the grow function of the FixedThresholdSRG look more clean
merge two files into utils.py
modify average contrast