add a bridge object, modify bus object to be able to connect to other buses or bridge...

add a bridge object, modify bus object to be able to connect to other buses or bridges without panicing

SConscript:
    add new cc files to scons
mem/bus.cc:
mem/bus.hh:
    implement addressRanges() on the bus.
    propigate address ranges to anyone who is interested stripping out ranges of who your propigating to (to avoid livelock)
mem/packet.hh:
    add intersect function that returns true if two packets touch at least one byte of the same data (for functional access)
    add fixPacket() that will eventually take the correct action giving a timing and functional packet, right now it panics
mem/physical.cc:
    Don't panic if the physical memory recieves a status change, just ignore.

--HG--
extra : convert_revision : d470d51f2fb1db2700ad271e09792315ef33ba01