The original forall x by P.D. Magnus, as well as Tim Button’s forall x: Cambridge, and the forallx: Calgary remix are now released under a Creative Commons Attribution (rather than the more restrictive Attribution-ShareALike license). The Fall 2018 version also incorporates some of Tim’s revisions for the latest version of forall x: Cambridge.
You can find all three on Github: forall x, forall x: Cambridge, and forall x: YYC.