Fix barrel overheat buffer too high at low levels

[calebchalmers]

Currently, there is a severe issue where the heat buffer is so high that we are unable to fire while the robot is at level one. This of course prevents leveling up and so you just can't shoot.

We can fix this by lowering the buffer and risking overheating, or keeping the current buffer but disabling it at lower levels and relying on drivers to watch their heat levels manually.

[calebchalmers]

This also depends on how tight the firing mechanism is mechanically. If we can stop shooting exactly when we need to, then we can lower the buffer without risking overheating.

[calebchalmers]

If we need to disable the buffer for low levels, maybe we can show a warning on the HUD to alert drivers that they need to be careful.

Requires #86