Add reviews

We can now add very simple reviews as git notes!

(and watch them float off into the void where noone will ever read
them).

README.md

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+# git-cr
+
+git-cr is a code review system which works at the commit, rather than PR, level.
+It is designed for use by teams practising trunk-based development, where
+reviews take place _after_ code is merged. If this sounds crazy, see
+[my blog post on the topic](https://tsvallender.co.uk/blog_posts/a-vision-of-continuous-integration).
+
+git-cr stores code reviews in the same repository as your code, using
+[git notes](https://git-scm.com/docs/git-notes). It allows you to review commits in
+your own editor, with no other special tooling. It’s designed to be incredibly minimal
+and meet you where you are.
+
+git-cr is a collection of BASH scripts, and should run on any UNIX-like system.
+
+git-cr is _very_ new and not ready for any kind of use!
+
+## Workflow
+
+```bash
+git cr n # Review the currently checked out commit
+```
+
+## Features coming soon
+
+- List reviews on your commits only
+- Tag necessary actions in reviews
+  - List actions needed
+  - Hook in your ticketing system to automatically make tickets from requested actions
+
+## Features coming maybe
+
+- Improved editor support for working with review files

git-cr-new.bash

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+#!/usr/bin/env bash
+
+################################################################################
+# git-cr-new
+# Adds a review at HEAD
+################################################################################
+
+set -o nounset
+set -o pipefail
+if [[ "${TRACE-0}" == "1" ]]; then set -o xtrace; fi
+
+USERNAME=$(git config user.name)
+TMP_FILE=".git/REVIEW_EDITMSG.tmp"
+MSG_FILE=".git/REVIEW_EDITMSG"
+
+main () {
+  # Get a formatted patch of the current permit as a starting point for the note
+  git diff HEAD~1 HEAD | grep -E '^[+-]' | sed -e '/---/i\\' | sed -e 's/^/# /' > "$TMP_FILE"
+
+  vi "$TMP_FILE"
+
+  # Remove comments
+  grep -Ev '^#' "$TMP_FILE" > "$MSG_FILE"
+  # Sign off
+  echo -e "\n--\nReviewed by $USERNAME\n--\n" >> "$MSG_FILE"
+
+  git notes append --file="$MSG_FILE"
+}
+
+main

git-cr.bash

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+#!/usr/bin/env bash
+
+set -o nounset
+set -o pipefail
+if [[ "${TRACE-0}" == "1" ]]; then set -o xtrace; fi
+
+while getopts "n" flag
+do
+    case "${flag}" in
+      n) git-cr-new.bash;;
+      *) echo "Unexpected option ${flag}"; exit 1;;
+    esac
+done