Merge branch 'v2.4'

regtest/drr/rt-restart/config

@@ -2,3 +2,10 @@ type=driver
 plumed_needs=boost_serialization
 plumed_modules=drr
 arg="--plumed plumed.dat --trajectory-stride 1 --timestep 0.005 --ixyz ala12_trajectory.xyz --dump-forces forces --dump-forces-fmt=%10.6f"
+function plumed_custom_skip(){
+  if [ "$(uname)" == "Darwin" ] ; then
+    return 0
+  else
+    return 1
+  fi
+}