Consolidate unfinished tasks and update documentation

docs/TODO.md

@@ -0,0 +1,23 @@
+## Current Tasks
+
+- Test stability with 18.432 MHz external oscillator.
+- Implement state machine for actual drying operation.
+- Rewrite code documentation with proper structure.
+- Check sensor measurements, conversion results and timer output frequencies.
+- Implement custom bootloader to facilitate software updates over serial port.
+- Make sure the initialization sequence can recover from as many technical
+problems as possible.
+- Implement I2C timeout or failing components may cause watchdog reset loop.
+- Detect brown-out and external resets during the initialization sequence.
+- Write isolated unit tests either with mocks or running in simulation.
+- Write simulated I2C components for more realistic testing with simavr.
+- MOSFET module needlessly specific? Rewrite as generic digital output?
+- Handle more parser commands like UPDATE, START and STOP.
+- Implement parser timeout for large input. Otherwise an UART RX buffer overflow
+will swallow the line terminator leading to the next command not getting parsed
+correctly. Also check for possible edge cases when the UART and parser buffers
+have different sizes.
+- Force system reset in Error() function?
+- Test efficiency for I2C via interrupts and ADS1115 continous mode.
+- Write cross-platform configuration header for different microchips?
+- Refactoring and optimization after all v1.0 features are finalized.