Automatically split into multiple sweeps()

For performing sweep() with SpectrumSensor, there is a time limit which
prohibits scanning many channels at once. We now split a single sweep()
call into potentially many ALH calls to avoid the time limit if necessary.
Fixed imports in alh-tx-test
Check "hello" response after programming and boot.
Merge branch 'chunked-sweeps'
Documentation update.
Initial implementation of the remote testing class
Add section about testing to README.
firstCall just to be sure.
Merge branch 'remote-testing'