New features
- Added automatic config migration.
- Added automatic config backup before migration.
- Added /vp version.
- Added additional configurable command messages.
- Improved /vp check with extra warnings.

Improvements
- Existing config.yml files are now updated without overwriting user values.
- Missing v1.3 config keys are added automatically.
- Command feedback is more configurable through messages.
- /vp status now shows plugin/config version and unsafe block count.
- /vp check now reports invalid unsafe block names.
- /vp check now warns when a custom rescue location exists but appears unsafe.
- Auto-registered worlds are now logged in console.