Option to use legacy UI

[boomboompower]

Brief Summary:
Allow users to use the old SkinChanger UI if they don't like the new one.

Usage:

1. Go into options
2. Set UI to legacy
3. Reopen UI in legacy mode

Justification:
Some users may be used to the old design, or may like the less-cluttered design in v2, this will allow them to continue using it. Similarly, the v2 UI does not have an issue with #21

This is an extension of #9 and #17

Steps:

• Write new UI ._.
• Create a setting, (bool/enum) to switch between the two
• Add button to option menu and hook it up to menu logic

[boomboompower]

This won't be going forward due to the quantity of UI's. Goodbye legacy UI

You will be missed :)