Bugfix init Jquery UI Sortable Widget +1.9
Stop the grid from trapping keyboard focus.
Fix keyboard focus getting trapped when cell has tabbable elements.

Added another focus sink just after the grid content and set focus
depending on the direction of keyboard navigation.
Merge pull request #462 from francoispluchino/master

[BUG] Jquery UI Sortable Widget +1.9 init bugfix
Don't initialize Sortable just for destroying

The `:ui-sortable` pseudo-selector filters out the element if it hasn't been initialized as a Sortable.
Merge pull request #494 from atesgoral/master

Improve jQuery UI Sortable fix
Fix #498 - Selections are not always maintained when filtering (Example 4).
Fix #496 - Improve the example to demonstrate proper use.
Add 'sortable' CSS class to sortable headers (#514).
Pass the right row to 'asyncPostRender' function (#505).
Added distance to prevent unintended reordering

Added a small distance delay on the sortable to prevent users from unintended
triggering of the reordering. (Happens all the time i'm using slickgrid).
i.e. the users tries to sort the column but fails since his mouse was still
on the move a little bit and 1px is enough to trigger reordeing here.
Please try, it still feels very responsive.
Replace 'hover' deprecated pseudo-event

'hover' pseudo-event has been deprecated in jQuery 1.9.0,
use of 'mouseenter' and 'mouseleave' instead.
Merge pull request #519 from loris/patch-1

Replace 'hover' deprecated pseudo-event
Changed distance value
Merge pull request #517 from ckosmowski/master

Add the distance delay to the header drag code.
Fix #520 - dropstart event not firing
Use of navigator.userAgent instead of $.browser

$.browser object has been removed from jQuery 1.9.0
Merge pull request #521 from loris/patch-1

Use of navigator.userAgent instead of $.browser
Added distance for dragging rows

Added distance to prevent users from unintended dragging of rows.
Merge pull request #523 from ckosmowski/master

Distance for dragging