gchecking gchecks that don't exist still gives invulnerability.

[Anna Bakker]

When mistyping a gcheck, for example gchecking 459 instead of 359 it says: "You are now invulnerable!" "You can return to your last coordinates with /greturn." "This code isn't linked to any alert."

###Other things it does:### * Saves what ever location you were at when you use the gcheck command and you can return to it using greturn. * Doesn't show that you are gchecking to other staff members. * Still turns invulnerability off after the time has ran out.

###What it should do (IMO):### * Say "There is no grief for this number, please double check what number you used" or something similar. * Not give invulnerability if it doesn't go to a valid gcheck.

[Riot]

Just a quick note, a member of staff has previously been caught abusing gcheck for personal transportation and was disciplined; anyone found doing this intentionally will be in trouble for bug abuse, which is not just demotable but a fully bannable offence.

Unfortunately there are no easy ways to tighten up gcheck to prevent all abuses while maintaining reliable functionality but I'll look into this.

[Riot]

refusing to continue if invalid gcheck number is entered. Resolves #84

→ <<cset e10313e381ed>>