Update tos-bsl for win32 python

tos-bsl uses the cp210xrt module, whose source is provided herein.  This
is a simple extension for Python that allows access to the
CP210x_WriteLatch function in the CP210xRuntime.dll.  The compiled
Python extension module is included, as well as the runtime dll and its
associated .lib and .h files.  The module was compiled using Visual
Studio C++ Express 2008, which is apparently the same version of the
MSVC used to compile ActivePython 2.7.1 from ActiveState, on which the
module was tested.

This uses the latest CP210xRuntime.dll and requires a 6.x version of the
SiLabs VCP to be installed.  Tested with VCP_Windows v6.6.1.

The code changes should not change behavior on non-win32 platforms.