Revert delete line and add navigation shortcuts

Added
* (ctrl y) - Delete line
* (ctrl alt right_arrow) - split vertically
* (ctrl alt down_arrow) - split horizontally
* (alt right_arrow) - navigate forward
* (alt left_arrow) - navigate back

Removed
* (ctrl y) - redo
* (ctrl alt right_arrow) - navigate forward
* (alt right_arrow) - Diff.NextChange
* (alt left_arrow) - Diff.PrevChange
* (ctrl alt down_arrow) - next occurrence
Merge pull request #8 from b2io/ctrl-y-delete-line

Revert delete line and add navigation shortcuts