added fromString method, improved code

Added PHP 8.0 support

Remove PHP 7.1 support, added utf-8 support for csv conversion #13

v0.2, better csv to json conversion, removed support for php 7.0

organize tests, fix error about splat operator where unpacking does n…

…ot work with assoc. arrays

modified the conversion method for json to csv to make it healthier w…

…here there may exist different properties for each object.

initial commit