This function will return the GM level of the account to which the invoking
character belongs. If this is somehow executed from a console command, 99 will
be returned, and 0 will be returned if the account has no GM level.

This allows you to make NPC's only accessable for certain GM levels, or behave
specially when talked to by GMs.

if (getgmlevel()) mes "What is your command, your godhood?";
if (getgmlevel()) goto Wherever;