Don't use the custom renders in the hotkeys editor on OS X

The standard controls aren't particularly usable, but the OS X
implementation of wxDVC doesn't actually support custom renderers and
not very usable is mildly better than entirely nonfunctional.

Updates #1589.
Don't reuse commit IDs for new commits after undo. Closes #1598.
Add an option to ignore uppercase words when spellchecking. Closes #1460.
Bump ICU version
Fix check for errors when compiling MoonScript