Fix some typehints.
Update API calls.
Fix some typos
Create modifier.nl2html.php

I know, there is `nl2paragraphs` too, but in my point of view,  nl2html ist an important plugin too.
Update src/docs/CHANGELOG.md
Merge pull request #653 from cmfcmf/patch-1

Create modifier.nl2html.php
Simplify code a little - one less namespace.
Clarify docs.
Make method comply with interface contract.
Fix some typehints.
Update API calls.
Fix some typos
Create modifier.nl2html.php

I know, there is `nl2paragraphs` too, but in my point of view,  nl2html ist an important plugin too.
Update src/docs/CHANGELOG.md
Simplify code a little - one less namespace.
Clarify docs.
Merge branch '1.3'