Pytest-visual

Fixes previous version for not including some library files in the distribution.

Major interface improvements.

**Full Changelog**: https://github.com/pytest-visual/pytest-visual/compare/0.2.2...0.3.0

* Fix `dash` silently producing error messages
* Render file and function name in UI

Refactors, fixes and documentation improvements.

First release with full local development functionality.

Features:
* Auto-diff compared to previous version
* Show diffs in browser, and accept/decline them
* manual, auto-yes and reset mode