Merge pull request #28 from Li-Ying/master

add a LAT2011 function
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
Merge pull request #30 from JieCyun/master

add two contrast enhancement functions
improve speed
Merge branch 'master' of https://github.com/yunfuliu/pixkit
Merge pull request #31 from b9707137/master

pixkit::labeling::twoPass speed up
add classification namespace
Add function of efficient DBS
minor fix
change pixkit-file and update to 0.5.1