Updated surface coeffs. for SPR mapper and added bounded resistance.
Updated tests. Seems to behave reasonably, but possibly some problems at
slow speed and high power.
Updated SPR Mapper tests.
Added Speed, power, resistance surface fitting and calibration tool
(Python)
Minor tidyup
Merge branch 'SPRMapper' of https://github.com/cowboy-coders/CyclismoProject into unstable