Update v3.1 for UTCOMP-3 and UTCOMP-PRO

[ArT]

Update v3.1 fixes few issues for UTCOMP-3 and UTCOMP-PRO. I'd like to thank you all users for sending reports.

v3.1 changelog:

• fixed bug with DS18B20 (A) and (B) config overwriting,
• fixed dimmer management in idle mode,
• display "--" instead of "0.0" for inactive engine or oil temperature,
• reset temperature readings after wake-up (before was displayed value before entering sleep mode),
• restored scale for fuel tank screen,
• buzzer info at first "cold-start" (cold-start is a first start after device reset)
• added possibility to VREF calibration (VREF is used as voltage reference for analog measurements).

Update is recommended for all users with first units of UTCOMP-3 and UTCOMP-PRO (firmware: v3.0.0, v3.0.1, v3.0.2 and v3.0.3). Update manual can be found in latest software (top menu "help" -> "manuals").

Small tip for UTCOMP-PRO users: tutorial for custom icons and graphics on display

update: it's already available more recent version