A bunch of changes, mostly to commanding

`sunDemo` now understands HEROES commands to start/stop tracking (0x1000 and 0x1001), sends acknowledgement commands (0x1100 and 0x1101), and changes modes to providing or not providing solution commands (0x1102).

It does not yet send predicted-exposure timestamp commands (0x1104) or any error commands (0x1103).

Steve coded up two command-line tools to:
* issue tracking start/stop commands (`CTLCommandSimulator`)
* see commands that the CTL receives from SAS (`CTLSimulator`)

Merging immediately