v0.7 - Sensor module

Add heater regulation

• Based on temperature reported by sensor module
• Set by heater/target_temperature
• Compensation of non-linear power

Custom messages can be printed on OLED display

• Used by recipes to inform about status
• Default message is serial number

Minor changes

• Sensor module onboard thermistor support
• Case fan control
• Faster logger (DMA support for UART)