Update mpc SHA

This MR updates the mpc SHA with some bugfixes and improvements.

This should allow the user to reproduce the video seen in !267 (comment 331467386)

Note that there are still stability issues, potentially from one of the following sources:

1. Simulator latency
2. Missing nav_base (or otherwise not used in the config files)
3. Parameter tuning

Fixing these issues is outside of the scope of this MR.

Closes #428 (closed)