Windows port

Currently, these changes are based onto of my earlier pull request. Let me know if you like me to rebase after the first pull request is merged.

Add SCons support for building wildtiger.lib & wt.exe

Checked in a special header called os_win_wiredtiger_config.h since scons cannot generate the autotools config.h header

Added:

    os_win directory full of Windows OS versions of WT OS compat layer
    os_windows.h for Windows (windows.h is already reserved by the OS)
    msvc.h for the compiler

In terms of preprocessor defines,
_WIN32 is Windows
_MVC_VER is the Microsoft Visual C compiler

Test framework update will be sent in a separate pull request

I will happy to address any KNF style issues myself. I tried to

Two hacky changes:
1. err.c - I inlined the ifdefs into this file for Windows
2. filename.c - I also inlined the platform ifdefs into this file

Todos left

    fallocate, and dlopen for standalone dlls
    crc intrinsic support