Libglcmsw

- included missing OpenCL source file
- included README.md
- included DOCUMENTATION.md

- added numba, pyopencl as dependencies
- implemented optimized CPU renderer with numba
- implemented a CUDA renderer with numba
- implemented an OpenCL renderer with pyopencl
- updated the SlidingWindow class so that it accepts the aforementioned 3 targets

- updated OS classifiers

- updated description of package in PyPI

- updated keywords for package indexing in PyPI

- uploaded to PyPI