Implement alternative pedal-to-torque transfer functions

[jr1221]

Description

Right now we have 4 types of transfer functions

• Derated (UNTESTED): for pit mode, to slow down torque as we get close to speed limit
• linear: for acceleration and endurance, simple 0-100 depression is 0-100 current
• Linear w/ regen accel: Part of the pedal is regen, then deadzone, then linear acceleration
• Linear w/ regen brake (UNTESTED): the brake pedal influences braking (deprecated)

The linear accel parts may benefit from a better curve.

Acceptance Criteria

• New curve is well documented with constants extracted, as well as a plot showing current versus pedal %
• New math is unit tested to best of ability
• New curve is disabled by default, but commented out code replaces linear_accel_to_torque w/ exp

Proposed Solution

Implement an exponential or at least a slower pickup curve to make the pedal less sensitive.

[jr1221]

Also implement max torque and kt constant with help from Ethan Markow's team.

[jr1221]

Also implement new mph math using wheel diameter, gear ratio (Abby Speckhals can help w/ that).