Kiss-headers

*Changes :* PR 4
- **Bugfix :** Accessing header that are named the same as a reserved python keyword. `From: eg`
- **Feature :** Possibility to invoke deep copy on `Headers` and `Header` objects.
- **Feature :** Subtract header from Headers by name (string) or object using operator `-`
- **Feature :** Add header object to headers using operator `+`

Thank to all early adopters !

*Changes :*
- **Support :** Add samesite and domain hint for Header class
- **Bugfix :** Should not allow key/attribute to have space in it
- **Bugfix :** Parse headers even if first n line(s) are not headers
- **Feature :** Support natively responses from Requests and extract headers properly

*Changes :*
- **Bugfix :** First batch of minors fixes after initial release 2

*first release*