Feature/bar styling

[daanvanhasselt]

Allow the user to pick one of 3 styles for the bottom bar shown during training:

• default (big blue bar)
• minimal (small centered text)
• none

Added 'PersistentStorage' classes from BM wiki to persist the bar style across sessions. https://wiki.bakkesplugins.com/code_snippets/persistent_storage/

[daanvanhasselt]

33