Code for PIR-based onion service lookups (client and server)

Ian Goldberg 746f980c29 Start the pirserver code 5 lat temu
Makefile 746f980c29 Start the pirserver code 5 lat temu
pirserver.cc 746f980c29 Start the pirserver code 5 lat temu
pirserver.h 746f980c29 Start the pirserver code 5 lat temu
protocol 746f980c29 Start the pirserver code 5 lat temu