continuously monitor profile switch allowing user to change it while running, update todos with cleanup tasks

fix display dimming based on profile switch setting at boot and timer start

add logic to read the profile selection switch

parameterize beep() to use different sounds for start/stop and interval alarms

audible alert on start/stop, simplify beep sound

add support for piezo buzzer beeps

configure temp probe handling to use /opt/devtimer/temp_probe symlink

further cleanup and tuning of footswitch debounce logic

tune footswitch debounce logic

implement foot switch handling as an isr with rudimentary debounce logic

canonicalize references to wiringpi methods and constants

enable basic footswitch control

initialize the time display on boot

remove unneeded globals file from repo, update todos

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

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

simplify thread start syntax

add basic scaffolding for footswitch control

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

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