the allow command now takes an optional uid argument for the user
to be granted temporary god status on the fileserver for maintenance.
this was kenji okomotos idea, so thanks :)
remove wstatallow and writeallow flags. instead, we have global:
int allowed;
that contains the uid of the currently allowed user id or -1
if permission checking is globally disabled for the fileserver.
when zero, normal permission checking takes place.
added int isallowed(File*) function that returns non-zero when the
context is the console, or the allowed user. this is also used internally
by iaccess(), so all the extra code of in the callers of iaccess()
is gone now.
dont conflate allowed user with noauth flag and auto-allow on ream.
the installer already knows about noauth and allow flags so theres no
problem with bootstraping.
