Make Blizzy Toolbar Optional

First pass on making Blizzy toolbar optional. Defaults off (like FAR and other mods doing both toolbars), checkbox in the Settings menu to switch between toolbars (requires restart or both show up). Probably need new art for the stock toolbar dimensions but for now it's using the blizzy 24x24 texture.

Also cleaned up a little in ShipManifestBehaviour (it wasn't doing anything outside of FLIGHT scenes, so I restricted it to only start during FLIGHT, seems to be working ok).