Minor code cleanups and re-scaling of rate calculations (for Betaflight v3.0.0 RC12).

1. Version updated to 2.5.5
2. Fixed #27 selecting rcCommand[all] will now scale pens individually.
3. Updated rate calculation to match new rates in Betaflight v3.0.0 RC12.
4. Updated Analyser window start/end times to allow for logs that start after or cross over the 5 min boundary (for those logging using a switch).
5. Corrected Log Sync Forward/Backwards buttons (thanks Joshua Bardwell for finding that one); the graph window now updates immediately after button is pressed.
6. Removed Obsolete parameters from header.