Lift 5: Misc updates/enhancements

[dpp]

https://groups.google.com/g/liftweb/c/sG2HWm4I3g0/m/lYvrejBkCAAJ?utm_medium=email&utm_source=footer

Andreas: I have a list of “small changes” we've done to Lift to make it better fit our needs. It's mainly configuration-stuff which lets you specify where “/lift” is (as a function), more configurable CometActors (wrt. initialization), bump to scala-xml:2.1.0 (and necessary changes to Html5Parser.parse).