In addition to changed merged below, commented out for platform os2 use of msvc,...

In addition to changed merged below, commented out for platform os2 use of msvc, mslib, mslink
as they cause test/import.py to fail.
I don't have an OS2 system to resolve the issues on.

Merged revisions 4065,4067-4068,4071-4072,4074,4076,4085,4111,4163,4222 via svnmerge from
http://scons.tigris.org/svn/scons/branches/vs_revamp

................
  r4065 | stevenknight | 2009-03-02 16:48:05 -0800 (Mon, 02 Mar 2009) | 42 lines

  Copy over changes by hand from branches/core (I was working in a
  directory pointing to the wrong branch):

  ........
    r4059 | stevenknight | 2009-03-02 06:54:13 -0800 (Mon, 02 Mar 2009) | 14 lines

    Initial prototypes of modules for architecture support (MSCommon/arch.py)
    and Visual C/C++ configuration distinct from (and in preference to)
    the Visual Studio configuration, incorporating configuration info and
    ideas from Jason Kenny's latest parts/tools/MSCommon work.

    This has a lot of cut-and-paste right now and does NOT actually work.
    In particular, there are no changes to the rest of the infrastructure
    to actually call any of this new stuff.  I'm checking these in so I can
    sync on other systems for continued development.

    The ultimate goal is for much of the current MSCommon/vs.py module's
    logic to migrate to MSCommon/vc.py, since that's what we're actually
    interested in configuring.

  ........
    r4058 | stevenknight | 2009-03-02 06:49:35 -0800 (Mon, 02 Mar 2009) | 2 lines

    Fix doc string.

  ........
    r4056 | stevenknight | 2009-03-01 06:10:31 -0800 (Sun, 01 Mar 2009) | 4 lines

    Change the sanity_check file for 6.1 per Jason's update.
    Add an optional version string argument to detect_sdk().
    Import directly from common, not SCons.Tool.MSCommon.common.

  ........
    r4055 | stevenknight | 2009-02-28 05:29:03 -0800 (Sat, 28 Feb 2009) | 5 lines

    Minor common.py enhancements:
    Refactor is_win64() to cache its return value so we don't have to hit
    registry every time we want to know if the OS is 64-bit.
    Accept SCONS_MSCOMMON_DEBUG=- to mean print debug messages to stdout.

  ........
................
  r4067 | stevenknight | 2009-03-06 04:59:21 -0800 (Fri, 06 Mar 2009) | 4 lines

  Fix entries in batch_file_map, after a double-check with the original code.
  Use a host_architecture of None in the map to indicate the "default"
  entry if there isn't a specific .bat file for our current architecture.
................
  r4068 | stevenknight | 2009-03-06 05:15:39 -0800 (Fri, 06 Mar 2009) | 2 lines

  Add include_subdir and lib_subdir data to the SDK definitions.
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  r4071 | stevenknight | 2009-03-10 07:42:53 -0700 (Tue, 10 Mar 2009) | 4 lines

  Capture basically working snapshot.
  src/engine/SCons/Tool/msvsTests.py and test/IDL/midl.py still fail,
  and code needs clean up.
................
  r4072 | stevenknight | 2009-03-11 06:38:37 -0700 (Wed, 11 Mar 2009) | 2 lines

  Fix path to Common7\Tools.  Find vs*.bat files.
................
  r4074 | stevenknight | 2009-03-13 17:11:55 -0700 (Fri, 13 Mar 2009) | 3 lines

  Import SCons.Tool.MSCommon.vc so it works regardless of other sys.path
  manipulation.
................
  r4076 | stevenknight | 2009-03-19 08:08:48 -0700 (Thu, 19 Mar 2009) | 7 lines

  Refactor SDK support:
  * New mssdk_exists() and mssdk_setup_env() methods as the primary
    public entry points.
  * Call internal sdk.*() utility functions that just return information
    (like the SDK structure) not handle the actual setting.
  * Give the VisualStudio definitions explicit settings for the SDK version.
................
  r4085 | bdbaddog | 2009-04-05 14:30:46 -0700 (Sun, 05 Apr 2009) | 3 lines

  Fix "can't find module vc" issue when building on windows.
................
  r4111 | stevenknight | 2009-04-19 07:47:47 -0700 (Sun, 19 Apr 2009) | 2 lines

  Doc updates for how MSVS_VERSION is used.
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  r4163 | bdbaddog | 2009-04-29 17:32:43 -0700 (Wed, 29 Apr 2009) | 4 lines

  Fix for bug 2405
  Also refactored some logic from Defaults._defines() into Defaults.processDefines() which is then used by msvs.py
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  r4222 | bdbaddog | 2009-05-31 17:01:22 -0700 (Sun, 31 May 2009) | 8 lines

  Added definition of HOST_OS|ARCH TARGET_OS|ARCH (For win32 only right now)
  Migrated some logic to determine arch from Tools/MSCommon -> Platform/Win32.py
  Fixed lots of minor issues with string values for directories, architectures, and registry keys
  Switch to find VS installs by registry (was using VC install location previously)

  Added but commented out that HOST_{OS|ARCH} and TARGET_{OS|ARCH} will become reserved var names in Environment()
  Need to resolve issues that SCons is issuing messages when SCons itself sets these variables.
................

git-svn-id: http://scons.tigris.org/svn/scons/trunk@4296 fdb21ef1-2011-0410-befe-b5e4ea1792b1