When colorMode is set to 0 via Retina::_init method, _retinaParameters's
colorMode variable is not correctly assigned.

This allows us to forget about the GTEST_(CREATE|LINKED_AS)_SHARED_LIBRARY
macros and to get rid of the dependency on cvconfig.h.

On my MacOS the output of the sphinx-build binary is the following:

Error: Insufficient arguments.

Sphinx v1.2b1
Usage: /usr/local/bin/sphinx-build [options] sourcedir outdir [filenames...]

...

I have installed sphinx, but without this change HAVE_SPHINX==0 for me, so I can't build docs.

WITH_WINRT -> ENABLE_WINRT_MODE;
Some temporary char* replaced with Ptr<char>;
Build fix for regular WIN32;
Windows Platform SDK and MSVC search added to cmake;
Warinig fixes.

Additional CMAKE flag WITH_WINRT added.

- Used lunix style slashes - works on most systems
- Removed all trailing whitespaces