fixes and improvements for oxygen sensor heating control

two more test for module rules

do not return from main() after test completed, cancel alerts fired ...

during tests

added tests for rules

adjusted test

back to programmer port /dev/ttyACM3...

experimental implementation of rules to notify about certain conditions ...

during burndown

refactored/renamed module "usart", use own implementation, added test, ...

updated comments, some cleanup

fixed some comments

improved comments, made parameter constant

added ability to set beep tone and a command to test/play with beeps

added tests for module "alert"

updated comments

adjusted test some more

new way of running tests

test new way of running tests

split tests into modules

- use size_t ...

- added tests
- some small improvements

- made function parameters readonly ...

- types with capital first letter
- updated comments and documentation

- one test was not included

- fixed obscure test failure

- use program space for unit test instances instead of data space ...

- "private" variables static
- removed updateDisplay()
- renamed some functions

sorted tests alphabetically (like in Jenkins)

added module strings with split function, added tests

finally updatePending is set at the right time so display is always ...

updated immediately

no need to wait for USART data to be sent with SLEEP_MODE_IDLE instead ...

of SLEEP_MODE_ADC

moved ADC and LCD pin constants to pins.h

uncomment assert

Another Jenkins test

Added comment, adjusted existing tests