Irccd: add more error properties, closes #754 Add two new properties in error messages: - errorMessage: the string message as-is, - errorCategory: the error category (e.g. server, rule). Adapt tests to test against the category.

root = true

[*]
charset = utf-8
end_of_line = lf
insert_final_newline = true
indent_style = space
indent_size = 4
trim_trailing_whitespace = true