This commit fixes following issues:
* Undo push of "deselect" does not work correctly with curves. [#6632]
* Hotkey (h) does not work correctly with curves. [#6633]
* If control points are hidden partially (not all are hidden at once),
curve object is not hidden. [#6633]
Issue regarding the way curve objects are shown in the object mode
when they are hidden remains to be solved. [#6633]
First commit!