Merge pull request #33 from JinYu-Syue/master

加入MSRCR函式
simplify AHE function
simplify AHE function
add function FAHE2006
add head
modify example file
add Gaussian diff observation method
add pixkit::qualityassessment::getDFTInfo
add pixkit::halftoning::errordiffusion::FloydSteinberg1976
bug fix
添加新的函數
Revert "添加新的函數"

This reverts commit 082e9621438dde6fb353351ec33957fb904eda9d.
test
添加新程式
意見更新
improve speed
add classification namespace
Add function of efficient DBS
minor fix
change pixkit-file and update to 0.5.1