v2.1.0

Add us (microseconds) mode. Protocols can now use a mixture of rows that define time units in us and rows that use ms (needs to be consistent within one row).
This also reduces the maximum allowed time between two pulses from ~6h to 1h, and with this constraint, it is still possible to run into overflow issues, this needs to be updated, probably by going from 32-bit to 64-bit numbers representing duration.