cocalc: merge /w master
cocalc: merge /w master

DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,DrXyzzy/smc,tscholl2/smc,tscholl2/smc