Merge remote-tracking branch 'ithinc/develop' into dev

Make the fork be based on 1.6pre21 version.

Conflicts:
	chrome/content/tabutils.js
	chrome/locale/de/preferences.dtd
	chrome/locale/es-ES/preferences.dtd
	chrome/locale/it/preferences.dtd
	chrome/locale/ja-JP/preferences.dtd
	chrome/locale/pl/preferences.dtd
	chrome/locale/pt-BR/preferences.dtd
	chrome/locale/ru/preferences.dtd
	chrome/locale/zh-TW/preferences.dtd
	install.rdf