Add simple code review checklist to PR template.

Add some checkboxes for common, mechanical parts that we should aim to hit for all PRs.

.github/PULL_REQUEST_TEMPLATE.md

@@ -9,5 +9,22 @@ What issue is this PR targeting? If there is no issue that addresses the problem
  - [ ] review
  - [ ] adjust for comments
 
+## Code Review Checklist - author check these when done, reviewer verify
+ - [ ] Code formatted with `scripts/format.sh`
+ - [ ] Changes have test coverage
+ - [ ] New exceptions, logging, errors - are messages distinct enough to track down in the code if they get thrown in production on non-debug builds?
+ - [ ] The PR is one logically integrated piece of work.  If there are unrelated changes, are they at least separate commits?
+ - [ ] Commit messages - are they clear enough to understand the intent of the change if we have to look at them later?
+ - [ ] Code comments - are there comments explaining the intent?
+ - [ ] Relevant docs updated
+ - [ ] Changelog entry if required
+ - [ ] Impact on the API surface
+   - [ ] If HTTP/libosrm.o is backward compatible features, bump the minor version
+   - [ ] File format changes require at minor release
+   - [ ] If old clients can't use the API after changes, bump the major version
+
+If something doesn't apply, please ~~cross it out~~
+
+
 ## Requirements / Relations
  Link any requirements here. Other pull requests this PR is based on?