[needs-packaging] Please package tabextensions3

Please package version 3 of tabextensions; the source package should be named tabextensions3.

Homepage: http://piro.sakura.ne.jp/xul/tabextensions/index.html.en
License: MPL (inside the jar, which is in the chrome/ directory of the individual .xpi packages inside the main .xpi)

Proposed binary packages which it should contain:
 - tabextensions3-informationaltab
 - tabextensions3-treestyletab
 - tabextensions3-multipletab
 - tabextensions3-viewsourceintab
 - tabextensions3 (meta-package depending on the 3 above packages)
 - mozilla-tabextensions (transitional package depending on tabextensions3; removed with bug #184121)

This has a general Feature Freeze Exception for Hardy, so if it gets done in time it would just need an Ack. from the Mozilla Team.