sim: Add relative break scheduling

Add schedRelBreak() function, executable within a debugger, that sets a
breakpoint by relative rather than absolute tick.

sim: Add ability to break at specific kernel function

Adds a GDB callable function that sets a breakpoint at
the beginning of a kernel function.

config: Add a --without-python option to build process

Add the ability to build libgem5 without embedded Python or the
ability to configure with Python.

This is a prelude to a patch to allow config.ini files to be loaded
into libgem5 using only C++ which would make embedding gem5 within
other simulation systems easier.

This adds a few registration interfaces to things which cross
between Python and C++. Namely: stats dumping and SimObject resolving

sim: Clarify the difference between tracing and debugging

This patch changes the name the command-line options related to debug
output to all start with "debug" rather than being a mix of that and
"trace". It also makes it clear that the breakpoint time is specified
in ticks and not in cycles.

scons: Add warning for missing declarations

This patch enables warnings for missing declarations. To avoid issues
with SWIG-generated code, the warning is only applied to non-SWIG
code.

Debug: Add a function to cause the simulator to create a checkpoint from GDB.

types: Move stuff for global types into src/base/types.hh

debug: Move debug_break into src/base

RemoteGDB: add an m5 command line option for setting or disabling remote gdb.

Updated Authors from bk prs info

New directory structure:
- simulator source now in 'src' subdirectory
- imported files from 'ext' repository
- support building in arbitrary places, including
outside of the source tree. See comment at top
of SConstruct file for more details.
Regression tests are temporarily disabled; that
syetem needs more extensive revisions.

SConstruct:
Update for new directory structure.
Modify to support build trees that are not subdirectories
of the source tree. See comment at top of file for
more details.
Regression tests are temporarily disabled.
src/arch/SConscript:
src/arch/isa_parser.py:
src/python/SConscript:
Update for new directory structure.