cleanup out of range temperature handling

fix leading zero suppression logic, generally tidy up temperature reporting

give time and temp led device objects more descriptive names

update todos

update todos

suppress leading zeros in temp display, add startup temp sentinel, reorg constants and globals

collapse temperature code and globals into main module, implement temp out-of-range signaling

add support for negative temps

added todo list

simplify thread start syntax

add basic scaffolding for footswitch control

add code to suppress bogus temperature reports from the 1-wire interface

add support for second display for temperature and display dimming in film mode

clean up function names, use consistent threading syntax for both display and temp management

restructure temp measurement to remove infinite loop from inside thread and move out to caller

cleanup cruft in ds18b20 module

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