Remove PackageInfoFor4.5.g, update PackageInfo.g

There is no point in trying to support 4.4 anymore.
PackageInfo.g: Unify various URL strings

Also, automatically use the current package version in the ArchiveURL
Add .gitignore
makedoc.g: call CopyHTMLStyleFiles()

This ensures *.css and *.js files stay up-to-date. In particular,
we can now remove the ancient and obsolete doc/manual.css in
the repository.