Significant rework of Packet class interface:

Significant rework of Packet class interface:
- new constructor guarantees initialization of most fields
- flags track status of non-guaranteed fields (addr, size, src)
- accessor functions (getAddr() etc.) check status on access
- Command & Result classes are nested in Packet class scope
- Command now built from vector of behavior bits
- string version of Command for tracing
- reinitFromRequest() and makeTimingResponse() encapsulate
common manipulations of existing packets

src/cpu/simple/atomic.cc:
src/cpu/simple/base.cc:
src/cpu/simple/timing.cc:
src/dev/alpha_console.cc:
src/dev/ide_ctrl.cc:
src/dev/io_device.cc:
src/dev/io_device.hh:
src/dev/isa_fake.cc:
src/dev/ns_gige.cc:
src/dev/pciconfigall.cc:
src/dev/sinic.cc:
src/dev/tsunami_cchip.cc:
src/dev/tsunami_io.cc:
src/dev/tsunami_pchip.cc:
src/dev/uart8250.cc:
src/mem/bus.cc:
src/mem/bus.hh:
src/mem/physical.cc:
src/mem/port.cc:
src/mem/port.hh:
src/mem/request.hh:
    Update for new Packet interface.

--HG--
extra : convert_revision : 9973d09ea4fa61795f23772a7d3995fa4df5c269