Fix MAC address parsing and serialization

[rgwohlbold]

Solves #46

• Eliminate undefined behavior in MacAddress::number
• Use network byte order (big endian) for MacAddress::number
• Use correct length for substr in constructor
• Write validation and serialization tests

I blacklisted the rule readability-function-cognitive-complexity globally since it flagged the test case without a reason, but I don't know whether that is the right call.

[Sohn123]

Solves #46

* Eliminate undefined behavior in `MacAddress::number`

* Use network byte order (big endian) for `MacAddress::number`

* Use correct length for `substr` in constructor

* Write validation and serialization tests

I blacklisted the rule readability-function-cognitive-complexity globally since it flagged the test case without a reason, but I don't know whether that is the right call.

In the documentation of the check is stated that by default the complexity of macros also counts. Maybe disable macros and try again? If this doesn't help, I would disable this check with a block NOLINT directive instead of disabling it globally.

[rgwohlbold]

Thanks for the hint! I updated .clang-tidy to ignore macros for this rule.

[Sohn123]

Nice that you added some tests to the parsing :) I think disabling the macros for this check is a fair call since macros are not a problem for human complexity in my opinion. So I would say let's fix this bug and