Release version 1.0.23.

Once again; here is the release checklist mentioned in #140.

- [x] Ensure that all the features, including updated TZ databases have already been committed to master before performing a release. Do not add new code in a release commit.
- [x] Ensure that your change log is up to date with all the changes prior to `1.0.24`. Do not edit the change log a bunch in a release commit.
- [x] Create a `git checkout -b release-1.0.24` branch.
- [x] Checkout your `release-1.0.24` branch.
- [x] Update the version number in `src/timezone.js` to `1.0.24`.
- [x] Update the version number in `t/version/get.t.js`.
- [x] Update the version number in `package.json`.
- [x] Ensure that the `CHANGELOG` looks reasonable.
- [x] Run `make clean && make zic && make && npm test`.
- [ ] Run `git commit -m $'Release 1.0.24.\n\nCloses #329.' -a`.
- [ ] Get the date of the commit and add it to change log.
- [ ] Run `git commit --amend -a`.
- [ ] Close this issue with that commit message.
- [ ] Run `git tag v1.0.24 && git push origin v1.0.24`.
- [ ] Merge `release-1.0.24` into `master` with `git checkout master && git splice release-1.0.24`.
- [ ] Push `master`.
- [ ] Wait on [Travis CI build](https://travis-ci.org/bigeasy/timezone) to pass.
- [ ] Run `make publish` which will clear out `.AppleDouble` and `.DS_Store` before publishing and publish the *build* directory.

Publish data files to `gh-pages`.

- [ ] Go to your checkout of the `gh-pages`.
- [ ] In the `code` submodule run `git fetch && git checkout v1.0.24 && git submodule update`.
- [ ] In the `code` submodule `make clean && make zic && make && npm test`.
- [ ] In the root directory run `NODE_PATH=code/build node data.js`.
- [ ] Run `git add v1.0.24`.
- [ ] Run `git commit -m $'Update GitHub Pages and data files for v1.0.24.\n\nSee #329.' -a`.
- [ ] Push commit with `git push origin HEAD`.

Publish data files as zip. (This is specific to my checkouts.)

- [ ] You no longer need to disable Travis CI, there is a `.travis.yml` in the
data branch.
- [ ] Go to your checkout of the data files.
- [ ] Add an entry in the `README.md` for v1.0.24.
- [ ] Run `rm -rf amd json jsonp`.
- [ ] Run `rsync -av /home/timezone/pages/v1.0.24/ ./`
- [ ] Run `git add .`.
- [ ] Run `git commit -m $'Update data file archives for v1.0.24.\n\nSee #329.' -a`.
- [ ] Run `git tag data-v1.0.24 && git push origin data-v1.0.24`.
- [ ] Push commit with `git push origin HEAD`.