Use posix stderr redirection (`2>` instead of `^`)

README: adding Table of contents

Add teams as code owners

fix typo

If I'm not mistaken, this command has been changed to use `plugin`, right?

Fish is deprecating `^` as a shortcut for stderr redirection.
Replace with the more common and compatible `2>`.

Fixes #609

use path queries compatible with old fish

Fix 'omf new' year in LICENSE files

Change License Year

Bump License year to 2018.

fix: #577 add environment sanity checks

Typo: Update example to use correct command

When creating new plugins the word 'pkg' does not exist for 'omf new' command.
The correct one is 'omf new plugin'.

Update changelog for v6

Fix #529

Readme updates

Notes for fish 2.2 kept in a new subsection.

Fixed License shield link in README.md

bump LICENSE year

Refactor command execution and help