We should implement a blacklist against GDB-defined default commands and keywords, so that we don't accidentally implement a command that overwrites an existing command.
A specific example of one that we overwrite is start (though we maintain similar behavior).
With my PR merged this now means that an attempt to override an existing GDB command will throw an exception. There is a whitelist for commands which are allowed to override existing commands which currently contains: "up", "down", "pwd", "search", "start".
Done in #543, thanks again @ZetaTwo o/ :beers: