mavlink-generator: use a type alias for the size of the array returned.
smavlink-gen: zero out the unused portion of the message array.
flight-transmit task: cleanups.
hx-stream (ivory): fix comment.
hx-stream (hs): take only the first 128 bytes.

  * TODO: all the constants should be in a single file.
commsec: better error reporting.
commsecServer: testing.
flight/commsec: simple array copy into package.
smaccmpilot: full crypto/hxstream tx works.