Add infrastructure

Add several tools to help with the extension development:

- Add .editorconfig file to set formatting options for the code editors.
- Add generateManifest.bash to generate the manifest.json file
  dynamically, from a template at templates/manifest.gjson. The
  manifest.gjson file can have lines defining what parts of the manifest
  are added for each target browser.
- Add release.bash to generate the extension ZIP files.
- Add Makefile to serve as a wrapper for the release.bash script.
- Add tagRelease.bash to help tag versions in Git accordingly.
- Add docs to explain all this new infrastructure (will need to be
  updated in the future with more details).

Change-Id: I698ffc59d0d2ec02b483935f7860e95760951a42
diff --git a/docs/development.md b/docs/development.md
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@@ -0,0 +1,8 @@
+# Development
+In order to work with the extension, take a look at
+[the docs](https://gerrit.avm99963.com/plugins/gitiles/infinitegforums/+/0991c69b3300b7c1e4b833bbb226f37bac7094c2/README.md)
+for this other extension that I developed. The infrastructure involved with this
+extension is very similar to the one for that extension.
+
+In the near future I will change the documentation for the other extension,
+which will allow me to update this article with more information.