For firebug1.2, branch.properties is in content/firebug directory. I
moved it so Firebug can read it to show its own version number in the
menu and as a tooltip on the statusbar icon. I updated the readme.
I may have broken the build.xml, which I don't use any more. Except
for install.rdf and update.rdf, the source tree is an image of the
extension directory: there is no need for a 'build'. Well except for
install.rdf I guess.