Multiple non-conflicting mods

[Marshall]

Two more minor features:
1. In Options, can now toggle on and off RA2/YR mods. So if you have, say, 100 mods, 50% of which are RA2 mods, and they're all intermingled, and you only want to browse the YR mods, then you can go to Options and say 'only show YR mods'.

2. Added ability to right click on a mod from the mods list and then 'Uninstall' (if the mod provides an uninstaller) or 'Delete' (if mod does not provide an uninstaller)

Also improved keyboard support - you *should* be able to control everything in Launch Base with the keyboard if you want to.