Get rid of PackageInfoFor4.5.g
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.
Cleanup PackageInfo.g
Fix LongTitle to not repeat package name
PackageInfo.g: don't set 'Autoload' (which only GAP <= 4.4 uses)
Add .mailmap
PackageInfo.g: update WWW and download URLs
build: makedoc.g updates VERSION using PackageInfo.g
PackageInfo.g: cleanup
Update CHANGES
Prepare release
PackageInfo.g: set IsMaintainer to false for Max N.
doc: change README to point people to GitHub issue tracker
doc: link to issue tracker from manual