Added BGAPI receive forwarding from Hercules -> WD -> Ground.

[zCoCo]

Process of impl. BGAPI Transparency/Passthrough mode. Currently sufficient to capture any boot (or even any bytes) from the FM1 Radio.

Also closed some bugs that showed up along the way that were necessary to RC5 testing:

• Closes #155 .
• Closes #151 .
• Closes #147 .
• Makes progress on #136 and #152 .