Interference with linum

[MartinRykfors]

Enabling key-leap-mode and then linum-mode causes display issues. So far I've just accepted this collision as a natural consequence of them both competing to set the margin.

I'm opening this issue because of the recent discussions on emacs-devel about handling the window margins: http://lists.gnu.org/archive/html/emacs-devel/2015-12/msg00066.html

If future versions of Emacs have a way for multiple packages to alter the margin, key-leap-mode should make use of this.