add TriggerSender

[steelec]

Create TriggerSender class in hardware and pull all the way through to the Trial level as per discussion w/ @theHilikus
skeleton outlined in df91dc31ad12553760eff484f6dfabb954cda9b9

[steelec]

implemented in https://github.com/neuralabc/spft-java/tree/enh-trigger, awaiting final device testing for merge

[steelec]

@ajhelum to confirm:

• inclusion of / enabling of trigger does not affect data recording
• inclusion of / enabling of trigger does not affect temporal precision of program (including smoothness of display to monitor)
• inclusion of / enabling of trigger does not affect CPU usage (which could result in any of the above)
• arduino trigger device does not affect EMG
• arduino trigger device does not affect EEG

[steelec]

implemented in https://github.com/neuralabc/spft-java/tree/enh-trigger, awaiting final device testing for merge

note other changes in this branch will include altering the meaning of presentation frequency to refer to # milliseconds for displaying each element of a sequence (from Hz, which was less precise) and likely some intermediate implementation of dynamic time warping ( #6 )

[ajhelum]

Arduino trigger device is receiving trigger signals from SPFT for all testing files (yaml) smoothly, in one java session. (no need to open fresh session for running separate files)
Tested with 1.4 jar (recent as of May 03 2023).
No trigger delays observed.

[steelec]

thank you for the testing, I think this is ready for merge into main

[steelec]

included here: #8

[steelec]

now #8 merged into main