0.8.0 - PEP484 support

PEP484 type hints support

• Now type hints relying on the typing module (PEP484) are correctly checked using whatever 3d party type checking library is available (typeguard is first looked for, then pytypes as a fallback). If none of these providers are available, a fallback implementation is provided, basically flattening Unions and replacing TypeVars before doing is_instance. It is not guaranteed to support all typing subtelties. Fixes #7

See documentation page for details.