Eml-parser

Added
- Simplify the code by using a sliding window body slicing method

Changed
- Use alternative URL extraction regular-expression
- Fix other regular-expressions (non-required escaping and ^)
- No longer support parsing h**xx**p(s) style URLs

Fixed
- In some cases the extracted features (i.e. domain, IP, URL, e-mail) were not correct due to wrongfully cutting through the body. This has been fixed by extending the text slice to a character unrelated to the match pattern.

Added
- Added **EmlParser** class in order to simplify inner workings.
- Moved typing annotations inline.

Changed
- Replaced a couple of regular expression used by simpler string operations for improved parsing speed.
- Renamed (internal) method *give_dom_ip* to *give_dom_ip*.
- Simplify mime-type detection

Deprecated
- Deprecated Python support for versions <3.7.
- Deprecated the usage of *eml_parser.decode_email* and *eml_parser.decode_email_b*. You should use the class instead.

Fixed
- Fixed docstrings.
- Removed any broad *Exception* usage.
- Fixed import orders.
- Extra requires option *file-magic* was renamed to *filemagic* -> pip does not seem to work with "-" in the name.