Removed all references to "mainconfig" from realms.c.

	Removed all references to "mainconfig" from realms.c.

	realms.c is now HUP-safe.  On HUP, it loads its configuration
	into a new data structure, and atomically switches between the
	old one and the new one.

	Right now, it immediately frees the old data structure.  It
	should really be placed onto a queue for later garbage
	collection, as a child thread may be accessing it.  That problem
	can be solved later.