* Add support for making non-buildable variants
* Add support for running a command to assign a value
* Update chrome-dev inheritance
* Add base variant
* Update manifest to auto-fill the version based on most recent git tag
* Add support for changing the default manifest
* Change the default manifest
* Move some manifest utility functions into manifest-util.js
* Move more manifest functionality into ManifestUtil
* Revert "Update manifest to auto-fill the version based on most recent git tag"
This reverts commit 2a66e40ff24f9dc545783503bcf3404f21148356.
