Fix allowed symbols in commands

[alerque]

I started matching ex commands with the list of predefined ones (not including default aliases). These names ale all alpha letters, a couple than have numbers, and few more that have underscores. I'm currently allowing that character range for user defined commands and aliases, but I see we have at least one exception to account for: exclaim is aliased to !.

That opens the can of worms that I'm not sure which symbols should be allowed in command names. What else might be allowed? Dashes? Other symbols? What should I account for?

@bovine3dom perhaps you can point me in the right direction...

[bovine3dom]

I only just saw this, sorry.

We have one reserved command name: you can't call any configuration key 🕷🕷INHERITS🕷🕷, so you can't have exactly that as an ex-command. Everything else except spaces is allowed.

Why do you have to account for what might or might not be allowed in a command name?