Add pier-core and pier.
Add pier-core and pier.

Version `0.2.0.1` of those packages was released today.

stackbuilders/stackage,Daniel-Diaz/stackage,spencerjanssen/stackage,ethercrow/stackage,jonschoning/stackage,fpco/stackage,massysett/stackage,wereHamster/stackage,mrkkrp/stackage,fimad/stackage,creichert/stackage,mstksg/stackage,mgajda/stackage,soenkehahn/stackage,iand675/stackage,asr/stackage,int-index/stackage,peti/stackage,michalkonecny/stackage,Shimuuar/stackage,athanclark/stackage,clinty/stackage,simonmichael/stackage