Add a new method called NRCIR2009 for color image enhancement
add a global based image enhancement method called LeeLeeKim2013
add a new color image enhancement method called LiWangGeng2011
move NRCIR2009 to src/enhancement folder and adjust the code comment in LiWangGeng2011
bug fixed
Merge pull request #51 from JinYu-Syue/master

Add a new method called NRCIR2009 for color image enhancement