implement basic multithreading between display and temperature logic

add module for reading and conditioning the temperature probe samples

fix typos and clarify key comments

added support for full table of correction constants from 60-80F for realtime, paper, and film

add function to return selected compensation profile

gave display constants unique names to accommodate multiple displays in the future

beep on start, only save last loop time if debugging

move gpio init under __main__, clarify compensation table comment

improved/fixed comments

fix time compensation logic, add beep(), add debug capability

implement basic temperature-dependent timing logic

factored led driver into separate file, general cleanup

initial checkin