ipatool: Add a diffstat to the report
pushpatches: add support for multiple reviewers

One can manually add multiple reviewers. It will still warn
in trac autodetection.
commit-report: Add a people summary
ipatool: Add support for multiple reviewers

This is a port of Petr's previous commit to the new übertool.
Merge branch 'multiple-reviewers'

Add support for multiple -r options to pushpatch and ipatool
ipatool: Fix reviewer handling
ipatool: Apply reviewers to all patches
Add an example post-commit hook
post-commit.example: Fix the doc comment
ipatool start-review: De-duplicate ticket numbers
Update README