Correct publish script

• Fix bug with publish script

Drop support for old Go versions

• Minimum Go version 1.18 is required.

Sunset support for older go versions than 1.16

• min Go version 1.16 required

Go mod and drop support for old go versions

• This version adds go mod and drops support for old go versions. Go 1.12+ is required now.
• Use Github actions for CI. Readme badge also updated.

Make Maildir directories creation be handled automagically

Now the standard Maildir directories - cur,new, and tmp will be automatically created - if they do not exist.

Better cross platform file handling

This release add better cross platform file handling using path/filepath instead of path package

Code improvements

This is release won't add any major changes to exposed methods. Following code improvements have been made:

• Use range keyword when iterating over arrays
• Use strings.TrimPrefix instead of strings.Replace

First release

Initial release