Change HotkeyPress event to be non-repeating (HotkeyDown to replace the
repeating case)
Fix shiftlag
Make toggle hotkeys only respond to the first SDL event.
Many iterations of review by: elexis
Test done by: Imarok
Comments By: vladislav, Stan
Reviewed By: wraitii
Fixes: #5055
Differential Revision: https://code.wildfiregames.com/D1398
This was SVN commit r23701.