Chimera: Engine CPS tooth count with skipped tooth, flash settings

[wocsor]

Chimera has an input for CPS pulse, and the interrupt for it is already set up. This feature, when implemented, can be useful for applications such as digital dashboards, remote starters, and upshift indicators. What needs to be done:

• setup new flash struct for engine RPM sensor (or maybe add it to VSS?)
• write config
• implement CPS tooth count and skipped tooth handling in cps_pulse to eng_rpm function
  Output of the engine RPM message is already handled and DBC is defined.

[wocsor]

commit aee8bbb should fix, but needs to be tested