Too many repetative but not-centralized strings

[tanabi]

As I'm working on the MUF commands, I'm noticing that the error message strings are repeated literally all over the place.

If we were to ever want to do any of the following:

• Change a message
• Localization
• Make these messages dynamic (i.e. load them from a file, make a MUCK command to alter them, etc.)

.... it would be a huge effort to do so.

I think localization is incredibly unlikely -- as far as I know, there's flat 0 demand for that -- but we should consider at the very least converting the repeticious strings to #defines that live in some logical location or locations -- some strings are truly global like "Permission denied" which surely must occur in almost every file in the source -- while others are pretty local to a .c file.

I don't really have a good plan of action here, yet, but I felt like I should call out the problem and this was beyond a simple TODO message :) Though I'm pretty sure I've done a TODO or two about this already.