Update README.md

Develop (TadasBaltrusaitis#619)

* Removing code duplication and getting rid of some C++ warnings due to float/double and signed/unsigned mixing.

* Fixing the screenshot functionality.

* Feature/code cleanup (TadasBaltrusaitis#573)

* Header guard cleanup (making sure naming is compliant with C++ standards and consistent).

* Removing un-needed nullptr checks.

* Removing SSE warnings for x64 builds (as SSE is enabled by default no need for a flag)

* Reverting Mat deletion

* Adding Visual Studio 2017 solution

* Feature/code cleanup (TadasBaltrusaitis#580)

- name of revision
- better scripts for model download (not only in Dropbox also OneDrive)

* Update the OpenCV constants to the corresponding ones in cpp namespace. (TadasBaltrusaitis#578)

Updating OpenCV macros.

* Slight change in packaging code (use a shared download script).

* Removing TBB dependency (TadasBaltrusaitis#590)

Removing a TBB dependence for code parallelization (done through OpenCV's parralel_for_

* Updating OpenBLAS (TadasBaltrusaitis#594)

Updating the 64 bit OpenBLAS version for Windows to 0.3.3 (50% perf improvement on certain machines)

* Ability to specify output image formats and removing unused quiet parameter.

* Update Windows download script (TadasBaltrusaitis#608) (TadasBaltrusaitis#610)

- Automatically choose correct path to the model files so that it works for both, source code compilation and binary use
- Use absolute paths in the system exists methods

* Updating version.

* Packaging code update.