CMS-4688 Sometime action in browser : hold a SHIFT  + ARROW_UP(ARROW_DOWN) does not work

Used the custom sort function on a numeric arrays in `TreeGrid` and
`Grid`.
Simplified code for key bindings in `TreeGrid`.
Merge pull request #1101 from enonic/CMS-4688

CMS-4688 Sometime action in browser : hold a SHIFT  + ARROW_UP(ARROW_DOW...