Feature
* Add beet.contrib.find_replace and generic pack selector ([`8e27ddd`](https://github.com/mcbeet/beet/commit/8e27dddc89ad2cec706ef0f66b2d0f14659055e6))
* Validate nested options ([`48d5f86`](https://github.com/mcbeet/beet/commit/48d5f8667d26ae3b140071b310fb213e9c2b397b))
Fix
* Validate extend once against content type when listing files ([`5e27735`](https://github.com/mcbeet/beet/commit/5e27735adad55327969c888d5afe5a51ebfef9e8))