F_intro

This pull request will be to merge the work completed in f_intro into develop.

f_intro handles the addition of a "intro" screen that consists of the company logo and a bear roar sound snippit being played before the menu appears. 
The logo fades from transparent black to visible over a couple of seconds, then stays visible for a second where the bear roar sound is played, finally it fades back to black transparent over a couple of seconds then moving on to displaying the menu.
The intro is not skippable
Anything not related to updating the display should probably go in the update function, or ina timer callback