Re-Minify only updated files

Imagine the following situation:

- You have prepared a deployment for your current project which is using MinifyJS module.
- In your deployment there are new JS files included but also some JS files changed
- After the deployment you need to minify the new files which is already possible through the UI
- You also need to re-minify the updated JS files - if you don't do that users will load the outdated versions of these files

Current situation:

- You need to know the changed files and chose the re-minify option from the UI
- It is not possible to only re-minify these files via drush - I'm currently working in a multisite project with 55 sites. I would need to do that 55 times...
- The UI does not identify changed files - even the filedate and size of the original file do not change

Additional issue:

- In the UI there is an option to only re-minify new files - this option is missing via drush

Expected behavior:

- During a scan the updated files are identified and flagged
- You see a special indicator in the UI that there are modified source files
- Via drush minifyjs there is an option to only re-minify updated files
- Since updated files are only discovered during scan the drush command should also have an option to automatically rescan before minifying starts
- Additional: re-minifying of new files (skip existing) should also be possible