API CHANGE: Add support for Pattern Generator setup via initTestboard.
Pattern generator commands consist of a signal (uint16_t) consisting of any
flag combination (see hal/constants.h) and a delay (uint8_t) which is performed
after the signals have been sent. There are 255 slots for commands in the PG,
the last entry should always have delay = 0 to stop the PG. This is checked by the
API.
Add pattern generator examples to testpxar, one for single ROCs, one for a full
Module. This completes the DTB configuration as reuqired for issue #10.