libtorc-core: Convert TorcPower to use TorcSetting
libtorc-core: Add Int type to TorcSetting
libtorc-baseui: Add UISetting widget

- very much a work in progress.
- creates a settings menu from the currently registered settings
- only implements boolean/checkbox settings at the moment
theme: Add media and settings screens

- still no mechanism for selecting media to play but now has fully theme
colour controls
- settings screen is just ugly...