better function categorization

util/stats/categories.py:
bit more stuff for categorizing functions

Add new function profiling stuff, wrap the pc_sample stuff into it.

SConscript:
Get rid of the pc_sample stuff and move to the new profiling stuff
base/traceflags.py:
DPRINTF Stack stuff
cpu/base.cc:
cpu/base.hh:
cpu/exec_context.cc:
cpu/exec_context.hh:
cpu/simple/cpu.cc:
Add profiling stuff
kern/kernel_stats.hh:
Use a smart pointer
sim/system.cc:
sim/system.hh:
Create a new symbol table that has all of the symbols for a
particular system
util/stats/categories.py:
change around the categories, add categories for function
profiling stuff
util/stats/profile.py:
No profile parsing and display code to deal with function
profiling stuff, graph, dot, and text outputs.

Totally re-work the way that jobfiles are done so there is more
information that can be used for other aspects of sending jobs.
New graphing output stuff with matplotlib.

util/pbs/job.py:
Shuffle code around and create the JobDir class which encapsulates
all of the functionality needed for making, organizing, and cleaning
a job directory.
Better status output
util/pbs/jobfile.py:
Majory re-working of the jobfile code.
A job file now consists of several objects that describe how
jobs should be run, it includes information about checkpoints,
and graphing.
util/pbs/send.py:
use the new jobfile code.
deal with the 15 character limit of pbs by truncating the name and
using the raj hack.
util/stats/db.py:
fix the __str__ function for nodes
provide __getitem__ for the Database class
util/stats/stats.py:
use the jobfile stuff to figure out what the proper naming
and organziation of the graphs should be.
move all output code to output.py, get rid of ploticus and use
matplotlib