v3.0.17

Fixed a bunch of bugs found while using this library in several projects, some of them in production.

• Fixed problem with empty strings in Tokenizer.
• Changed behavior of the .remove_item() method to compare using identity.
• Added new method .parse_file() method to simplify working with files.
• Fixed problem with tokenizer & nonpair tags without spaces.
• Fixed problem with re-ordering of the parameters when setting them.
• Fixed pypi badge in readme.
• Respect spaces in the Comment objects.
• .__copy__() and .__deepcopy__() methods implemented also for Comment.