Merge branch 'v2.1'

regtest/mapping/rt39-mpi/colvar.reference

-#! FIELDS time p2.sss p2.zzz p3.sss p3.zzz
+#! FIELDS time p2.spath p2.zpath p3.sss p3.zzz
  0.000000   1.9434   0.0001   1.9434   0.0001
  0.250000   1.0090   0.0001   1.0090   0.0001
  0.500000   1.0579   0.0001   1.0579   0.0001

regtest/mapping/rt39-mpi/deriv.reference

-#! FIELDS time parameter p2.sss p2.zzz p3.sss p3.zzz
+#! FIELDS time parameter p2.spath p2.zpath p3.sss p3.zzz
  0.000000 0   2.9260   0.0007   2.9260   0.0007
  0.000000 1  -3.2521  -0.0011  -3.2521  -0.0011
  0.000000 2   4.2465  -0.0003   4.2465  -0.0003

regtest/mapping/rt40-mpi/colvar.reference

-#! FIELDS time p2.X p2.Y p2.zzz p3.X p3.Y p3.zzz
+#! FIELDS time p2.X p2.Y p2.zpath p3.X p3.Y p3.zzz
  0.000000   1.9434   2.9434   0.0001   1.9434   2.9434   0.0001
  0.250000   1.0090   2.0090   0.0001   1.0090   2.0090   0.0001
  0.500000   1.0579   2.0579   0.0001   1.0579   2.0579   0.0001

regtest/mapping/rt40-mpi/deriv.reference

-#! FIELDS time parameter p2.X p2.Y p2.zzz p3.X p3.Y p3.zzz
+#! FIELDS time parameter p2.X p2.Y p2.zpath p3.X p3.Y p3.zzz
  0.000000 0   2.9260   2.9260   0.0007   2.9260   2.9260   0.0007
  0.000000 1  -3.2521  -3.2521  -0.0011  -3.2521  -3.2521  -0.0011
  0.000000 2   4.2465   4.2465  -0.0003   4.2465   4.2465  -0.0003