MG_polyRivet and MG_pathSpine

MG_polyRivetGUI start
MG_pathSpine minor fixes
Merge remote-tracking branch 'upstream/update1.2' into update1.2
MG_polyRivetGUI done
gitignore prep
Merge pull request #23 from tokejepsen/update1.2

MG_polyRivetGUI