Fix sig violation detection

Especially for posts with centred images and pages with more than one post from the user
Use the Firefox SDK tarball instead of the git repo

addons.mozilla.org will reject packages uploaded using the git version.
Remove comment in Chrome/manifest.json

Confuses the Chrome store
Remove Chrome update URL

Disallowed by the Chrome store
Add +build/chrome-store-upload.zip to the Makefile
Add "posts by user in thread" link
Add website permissions for Chrome/manifest.json in Makefile
Clean Chrome and Firefox directories in `make clean`
Merge branch 'master' of /home/andrew/games/elite/dangerous/mod-tools/BabelExt

Conflicts:
	Chrome/manifest.json
	lib/config.txt
Add permissions to Chrome/manifest.json
Updated version number to 1.2

Actual command: ./release.sh 1.2
Rename "inject_script()" to "run_script_in_embedded_page()"

In hindsight, the latter didn't communicate its intent very well
Use an unpacked version of jquery-observe.js
Updated version number to 1.2.1

Actual command: ./release.sh 1.2.1
Add temporary icon
Updated version number to 1.2.2

Actual command: ./release.sh 1.2.2
Updated version number to 1.2.3

Actual command: ./release.sh 1.2.3
Thoroughly test signatures