Fix go to command definition when it is a custom label referencing command

[PHPirates]

Fix #1782

Summary of additions and changes

• There was still an old usage of LatexLabelReference which was creating such a reference for a LatexCommands, but that's moved to the ParameterText with a LatexLabelParameterReference, so it was blocking the correct reference to the command definition.
• Include custom label referencing commands in label resolving (why wasn't that present already...)
• Fix TEX-109 (simply missing magic information, that loadclass adds .cls extension)
• Fix TEX-20: Make \url a verbatim command to allow using % without escaping them
• Fix TEX-15: warn against usage of \catcode

How to test this pull request

\documentclass{article}
\usepackage{url}
\newcommand{\tablelabel}[2]{
    \ref{#1}
}

\begin{document}
    \label{argument}

    \tablelabel{argument}{another} % command resolves to definition, and argument resolves to label (both of these were not working)

    ~\ref{argument}

    \url{https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwj8qK3bgYPvAhWOxIUKHWfeBZcQFjAAegQIBxAD&url=https%3A%2F%2Ftex.stackexchange.com%2Fquestions%2F224506%2Fspecial-character-in-url&usg=AOvVaw0YtiamRY59mbdNzg4rVKOH}
    This \url|https://%.com| is not an url, but it shows verbatim.

\end{document}