Finish fixing Message errors

Fix 3 of the last 4 errors of TimeHelper

Fix a blunder with the test version of call()

Attempt to calm down clang-tidy and fix some stupid warnings in my CRC code (nothing much, just turned the counter int in a for-loop into a uint32_t to shut gcc up)

Comment out the empty constructor to mute clang-tidy's warning about trivial constructors

Use assertions to ensure that dates make sense and change the implementation of operators <= and >=, increasing the readability

Clang-tidy complaints, so the if-else structure of the implementation of the operators changed. The code is a little bit ugly so it should be evaluated

Fixed a bug: In utcTime function, when the year was leap year, the extra day was substracted two times instead of one.