Implement flex fuel sensor temperature input

[mck1117]

Flex sensors send fuel temp too, let's decode it.

[diy-efi]

Continental flex sensor fuel temperature can be read with the following formula: (Temperature = (41.25 * pulse width(ms)) - 81.25). 1000μs = -40C and 5000μs = 125C

[mck1117]

this is done