Also simplify logic on all ARM-based interrupts. Now, it is REQUIRED to properly configure interrupt priority. USART should have highest priority, followed by Stepper, and then all others.

Reference #9983

Followup to #9985

Fix #9477

Implemented for LPC1768.

To reduce confusion over the current timer count vs. the compare (aka "top") value. Caution: this re-uses the function name, changing its meaning.

Misc formatting

Some also get a `HAL_timer_interrupt_enabled` function.

* Update persistent_store_impl.cpp
* Remove define BYTE from serial functions since Arduino docs typically show 0 for the normal case.

Clarify the HAL_adc_get_result method to make sure correct values enter the filters

HAL: Fix the PID control loop for non-AVR platforms

Formatting tweaks

correct array initialization & remove test code