Some to correct missing files from previous PR to completely avoid
HardwareTimer Class (reduce overhead). Some changes to formatting.
Changes to DMA ADC to work correctly.
Change to F1 sanity check.
Adding files for STM32F1 HAL based on libmaple/stm32duino core.
Current persistent_store uses cardreader changes to be sent in separate
commit, but could be changed to use i2c eeprom.