Fuller trigger & strobe support

Polarity of the trigger can be set, and strobe on pin 1 is supported.  Extension to pins 2 and 3 would be easy, but it's rarely used.
If you could— this change has made it look significantly weirder to me in both my local vim and the github webui, though it looked pretty bad in the webui before too.

Alternatively, just retab the whole file and line things up using only spaces.