Usage : exec <lpc code>

Exec can be used to execute a small amount of lpc.  What the function does is
write a temporary file call ~/exec_tmp.c and call a function containing the
code you provided on that object.  It will delete everything when it is finished
and clean up everything.  It will also print whatever return value is passed.

Examples:

exec return users()
exec return query_ip_number(this_player())
exec string s; s = "frog"; s += "fish"; return s
