So that "http_server.h" does not have to include "serval.h" which
creates a circular dependency.
Remove the __SERVALDNA__HTTP_SERVER_IMPLEMENTATION hack from
"http_server.h"
- completely event driven and non-blocking
- modelling of tx & rx serial buffers that will truncate on overfilling
- each radio takes turns to send a packet, with approx TDMA overhead
Simulates +++ / ATO capture, as well as enabling and disabling
RSSI output with at&t=rssi and at&t commands.
Implements some data rate throttling to match real radio, but
untested.