Damien George 7e90e22ea5 mpy-cross: Add --version command line option to print version info.
Prints something like:

MicroPython v1.10-304-g8031b7a25 on 2019-05-02; mpy-cross emitting mpy v4
2019-05-07 13:54:20 +10:00
..
2017-07-18 11:57:39 +10:00
2017-07-18 11:57:39 +10:00