Allow Modulation bits to be manually defined

[Capkirk123]

Currently, the number of modulation bits an antenna on a craft is allowed to use is defined as one-half the antenna tech level, while ground station antennas can have their modulation bits defined directly.

This isn't a huge issue currently because connections are limited by the slowest peer, and therefore ground stations force all craft connected to them to operate at their (historically accurate) modulation bits, but it means craft-craft connections can achieve unrealistically high data rates.

However, Skopos is a lot more sensitive to historical comms technology, and potentially would benefit from being able to manually define modulation bits per tech level.