Unevilize vn(4) somewhat: 	1. implement read-only ability 	2. make it play nice with cdevsw (use cdevsw_remove() uon kldunload)
Unevilize vn(4) somewhat:
	1. implement read-only ability
	2. make it play nice with cdevsw (use cdevsw_remove() uon kldunload)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase