Highlight Folding Markers
It regards to issue #38 at kate's repository
- Added folding markers highlighting
- Added attribute "length" to Folding class.
- Added movingRange attributes in kateviewinternal to keep the highlighting state
- Added updateFoldingMarkersHighlighting and findMatchingFoldingMarker functions to update the highlighting of Folding Markers. It works both ways: from a start folding marker to end, and from end to start.