Reduce starting speed to avoid slipping

For BitBot PRO, the higher starting speed can cause the wheels to slip when starting up (depending on surface). This causes inaccuracies in movement. This release reduces the start speed to minimum sensible.

Improve Arc accuracy

Constrain speed so inner and outer wheel speeds are achievable.
Add fudge factor to angles to improve accuracy for various speeds and radii

Fix more Norwegian typos

v2.1.11

Merge branch 'master' of https://github.com/4tronix/BitBot

Fix typos in nb strings

Fix typos in nb strings:
I fixed a missing " and a , 

Correct nb strings file name

The new Norwegian (nb) strings file had an incorrect name, so was not being used.

Handle out of range speeds. Update Norwegian strings

Clamp speeds to 0-100, or -100-100, as appropriate
Update Norwegian text strings

Fixed multiple Stop commands

Sending multiple Stop commands to BitBot PRO caused issues. Also added back the servo controls for BitBot PRO

Add Directions for Arcs

Arcs can now move forwards/backwards, left/right
Also removed all extraneous semicolons

Protect against multiple motor commands

Don't call underlying PID control loops if same command is being sent. Also, kill any existing PID control before starting another

Add Buzzer volume controls

Add buzzer sind for selected time, a new buzzer volume block and create a "General" sub-category