miurahr/py7zr: Support zstandard, memory IO API and more

Added Support memory API.(#111, #119) Introduce read(filter) and readall() method for SevenZipFile class. Support ZStandard codec compression algorithm for extraction.(#124, #125) Changed Drop pywin32 dependency Introduce internal win32compat.py Archive: Looking for symbolic link object in the archived list, and if found, record as relative link.(#112, #113, #122) Removed Revmoed requirements.txt. When you want to install dependencies for development you can do it with 'pip install -e path/to/py7zr_project