Config error messages

[flatcap]

I've been looking at the error message for the config.
They're a 50:50 mix of "option X" and "variable X".

Does anyone have a preference?

There are about 30 of each:

Option:

• Invalid value for option %s: %ld
• Invalid value for option %s: %s
• Option %s may not be empty
• Option %s may not be negative
• Option %s may only be set at startup
• Option %s must be between %d and %d inclusive
• Option %s must not contain shell metacharacters: %c
• Option %s: %s is not a valid authenticator
• Set option %s before setting %s

Variable:

• %s: unknown variable
• Can't query a variable with the '%s' command
• Can't set a variable with the '%s' command
• Command '%s' can only be used with bool/quad variables
• Config variable '%s' is deprecated
• No such variable: %s
• Unknown variable '%s'
• Variable '%s' has an invalid type %d

[flatcap]

I've gone for 'option'.