Install separate panel power feed gland in firewall

A separate pass-through gland for the panel power feed was installed, in accord with best practise. The idea is to keep high current paths away from the main engine sensor wiring loom bundle, which also has bundled with it the ignition system grounding circuits. In the event of a fire involving destruction of the cable wiring (unlikely, since this is fused forward of the firewall) the ignition grounding cables are most unlikely to be immediately affected, so the engine is more likely to keep running for a longer time in the event of this extreme circumstance