UI changes and texture compression

Mikoverse Client Playtest

This update includes work-in-progress UI changes and texture compression for registered avatars. [list] [*] The main interface is now toggled on and off with Escape instead of Tab [*] Logout/Quit moved to the main menu [*] Registering an avatar will generate compressed textures that are saved on the server [*] Existing registered avatars can have compressed textures added by going to the Edit screen for the avatar [/list]