WIP: Configuration and files for upload to PyPI

• These changes contain the minimum necessary files and configuration required to prepare miniff for packaging and uploading to PyPI.
• The end goal is to have a single command installation (pip install miniff) for the users who want to install and use miniff.
• A source distribution and a built distribution will be built and uploaded to PyPI to achieve this.
• Cython source files (.pyx) and .c files are included in the list of files that will go in the source distribution so that users can install miniff without needing to have Cython available. These files are listed in MANIFEST.in along with other required files.
• As of now, the packaging and single command installation is tested to be working fine locally on Linux as per the steps in issue#14
• These steps are also added in the CI. There could be a cleaner/better way of doing this, let me know.

@pulkin @anton-akhmerov, I've created this draft merge request for code review purposes. Can you take a look at these changes and comment if anything is missing or needs to be corrected?