attributes line `wrap_links` not configurable on the library level

[098799]

• Version by html2text --version
html2text==2019.9.26

In the current version of html2text, if one tries to use the library through html2text function or HTML2Text class, there's no way to specify variables such as wrap_links for the program. It would be preferable if the class HTML2Text allowed configuration regardless of the cli usage. Currently, the package is not usable as a library.

[098799]

Issued a PR, but it can't be merged in the current state, as hits mypy's bug:
#309