Made a single registry of output plugins which gets populated on init with classes to output on a socket, print to screen, database, etc. Next step is to implement a SQLite database class.
Right now there's a 1e6 gain block in there because old USRP spit out roughly 1e6x data as USRP2. Haven't investigated this for USRP vs USRP2 yet. Don't know why blocks care, actually.
