Parse html in multipart/mixed

Merge pull request #19 from k-yomo/support-html-in-multipart-mixed

Add support for html in multipart/mixed

Parse top-level multipart/related

v1.1.0

test brought in line with the others

Go Mod fixed

Merge pull request #15 from xgess/xgess/fix-gomod

fix go.mod to this repo

First tagged release

First tagged release. All subsequent releases will be tagged according to semantic versioning. No BCs were introduced but bunch of issues were resolved.