Improve error messages

[mpf82]

Is your feature request related to a problem? Please describe.

Error messages could be improved, related issue: #115

Describe the solution you'd like

The actual variable should be part of the error message, where it makes sense.

e.g. instead of raise TypeError("'name' (string) should be from 1-30 chars.")

it could be raise TypeError(f"'name' (string) [{name}] should be from 1-30 chars.") - so the actual name can be seen.

Same goes for other checks, e.g.

TypeError("'field_type' (string) must be in [" + ", ".join(_type2rfc) + "]") -> TypeError(f"'field_type' (string) [{field_type}] must be in [" + ", ".join(_type2rfc) + "]")

TypeError("'direction' (string) must be in [" + ", ".join(_direction2rfc) + "]") -> TypeError(f"'direction' (string) [{direction}] must be in [" + ", ".join(_direction2rfc) + "]")

and so on.

Variables do not neccessarily have to be in square brackets, but I've seen it in print (f"[{datetime.utcnow()} UTC] {origin} '{log_message}'") - plus it helps to figure out if there are leading/trailing spaces in a variable.

[bsrdjan]

Thanks @mpf82 for suggestion, brackets are used for timestamp log only