fixes #1570 Remove overlay hidden for column
fixes #1570
Merge branch 'feature/issue-1570' into develop
performance optimization (remove Array.prototype.slice)
fix accidental global variable
missing semicolon
optimize performance
speedup demo pages
fix unsupported window.scrollY, window.scrollX in IE8-11 (#1574)
Fix for ColHeader not passing phantomjs tests
Merge branch 'develop' of https://github.com/warpech/jquery-handsontable into feature/issue-1573
#1573 - Fix for tests failing