Bulk update files

[mbrukman]

It would be nice to have a utility to bulk-update all files of a particular type or language and insert a comment at the top of the file.

Proposed feature evolution:

• v1: prepend given license to all files that match a filter or just in a list
• v2: detect whether or not a license header already exists and avoid modifying that file

[mbrukman]

Given the in-place file modification was implemented, files can now be updated in bulk via:

find . -type f -name \*.sh -exec /path/to/autogen -i [options...] {} \;

So the v1 feature can be considered implemented. However, the tool will still prepend a license even if a license header already exists, so this operation is not idempotent as requested for v2.