Fix #417 - Header buttons not working in FF.
Add an option to force sync scrolling.
Minor cleanup.
Add an "active" CSS class to the active row.
fixed bug where ancestor-bindings were not removed in case the
canvas-element is detached from the dom before the grid-instance is
destroyed
fixed missing space when applying 'active' class to row
fixed formatting
Merge pull request #431 from ClemensSchneider/active_row_class_fix

Missing space for 'active' class of active row
Merge pull request #430 from ClemensSchneider/safe_ancestor_binding

fixed bug where ancestor-bindings were not removed
BREAKING API CHANGES

New events:
+ onBeforeHeaderRowCellDestroy
+ onHeaderRowCellRendered

Renamed events:
  onHeaderRendered -> onHeaderCellRendered
  onBeforeHeaderDestroy -> onBeforeHeaderCellDestroy

New methods:
- setTopPanelVisibility
- setHeaderRowVisibility

Removed methods:
- showTopPanel
- hideTopPanel
- showHeaderRowColumns
- hideHeaderRowColumns
Fix #432 - check hasOwnProperty() in for (... in ...) loops over arrays.
No need to namespace events on elements that we remove on destroy.
Fix #428 - scroll the main area when the header row is scrolled.
Fix #376 - size the header row spacer to the right width
Fixed #417 - checkbox select column handling for empty grids
Fix #420 - removed an unused option
Merge remote-tracking branch 'mleibman/master'
Fix #445 - Reset active cell when its row no longer exists.
Fix #421 - Don't close the header menu on scrollbar click
Fix #398 - Add a "defaultSortAsc" column option.