Only have the common channel accessible via intercom and perhaps hand held radios

[Zundy]

As the title says. Make it so you can only speak and listen to common channel via intercom and hand held radios. Department radio can stay on the headset.

This will give antags and edge, reduce common spam and reduce the omniscient power of the AI (no more ";help"). Also silly miners will need to turn on their sensors or die ;^)

Thoughts?