Rudder

In enforce a file content, if we want to zone edition and migrate texts, it migrates all lines that matches any of the line
this is convenient in most case, but sometimes we want to migrate a complete block, not line by line (think of logrotate, if we do migration, it will "steal" a closing } from another block )

We should have an option to either:
- migrate the block (what we had before)
- migrate line per line (what we have now)