Improve flow and SDK update

Minor updates to Help and Calibration displays.

Fix for potential crash should iPhone gyroscope not be functioning correctly.

App metadata updates, no changes to code.

A minor code fix to prevent a potential crash on startup.

Update to pitch and roll calibration bias logic.  Now when pitch or roll bias is in use, text is shown on the main screen to indicate this.

A custom audio feature has been added to RevelLevel.  Now instead of just the 5 pre-recorded voices for level and not level states, the user can record their own voice.  The app user can record whatever they want, and it will play when the level or not level state is determined.  3 seconds of audio can be recorded for each level or not level states.  Maybe catchy or humorous phrases are wanted.  Maybe level notifications in a language other than English is wanted.  Whatever you dream up ... now you can customize this app to announce in your own voice!

Bug fix for background color not changing for out of tolerance wheel values when sound is disabled.

Added new voice.  Professional woman saying 'Level' and 'Not Level.

Minor user interface modifications to support iOS 13.

Sounds can now be used to level your van with this app.  You can now set a level tolerance value and chose a sound pair.  One sound will be played if you are out of the level tolerance range.  Another sound will play if you are within the tolerance level.  For example: You can choose a level tolerance of 2 inches.  Then make sure the audible icon on the upper left of the main display is activated and put your phone on a flat surface.  Get in the driver's seat and start moving your vehicle.  The app will tell you when you are out of and within the 2 inch level tolerance limit.