Merge branch 'v2.3' into v2.4

user-doc/Installation.md

@@ -704,6 +704,11 @@ ld: TOC section size exceeds 64k
 \verbatim
 ./configure --disable-ld-r
 \endverbatim
+- On Cray machines, you might have to set the following environment variable
+  before configuring and building PLUMED (reported by Marco De La Pierre):
+\verbatim
+export CRAYPE_LINK_TYPE=dynamic
+\endverbatim
 
 \page CodeSpecificNotes Code specific notes