Make repository_age() "history rewrite safe"

Change commit date to author date, so that the repo age doesn't change if history rewriting tools (such as amend, rebase, filter-branch) are used.
git-squash: add --me flag to flatten the current branch
Release 1.9.0
fixed `grep: invalid max count`
add output of file being processed
add missing hashbang
remove /usr/bin/env from hashbang
fix complains from `checkbashism -px`