add utility for creating Moodle feedback files

I used this script to create feedback files that were then uploaded to Moodle to avoid squeezing textual feedback into the spreadsheet (which is then presented poorly on the Moodle). In fact, I used it twice in CS1999: first as a way of distributing unique login credentials to each student (see comments in the script: "Special use") and then, after marking, for uploading the feedback comments (which were presented as formatted HTML — including a link to Calendly for code review). The script has a default text in HTML which iirc is because Moodle doesn't escape it, i.e., it's displayed as HTML if it's viewed in place.

For the marking case, I extended this script to customise the feedback file's contents with data injected by reading out of my own (local) file with all the feedback in it (doing Markdown → HTML on the way in)... but that's a bit custom and isn't the useful bit.

Historic note: We used Feedback files in CS1870 too: in that case annoted copies of the PDFs the students had submitted. That required a bit of a file munging (in Python) to check the very specific filenames were being respected. Moodle's feedback file mechanism is — of course — pretty idiosyncratic but it's better (imo) than putting feedback text into the grading sheet and losing all civilised formatting because it all runs together. Ugh.

Software offered as is, user runs at own risk, no receipts offered.

Feel free to ignore :-)