p:columns experiment in p:row

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12008 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
add setter

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12009 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
better selector

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12010 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Improved dynamic columns inside columnGroup

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@11998 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Merge branch 'master' into 5.1.x