Look for CMake 2.8 if available on system

We require at least this version, and if there is a newer, it will
probably break due to lack of backward compatibility anyway.

configure

@@ -89,8 +89,12 @@ option_check=yes
 # this variable will get feature options
 FEATURES=
 
-# command that launches cmake
+# command that launches cmake; look for 2.8 if available
+if which cmake28 >/dev/null 2>&1; then
+CMAKE=cmake28
+else
 CMAKE=cmake
+fi
 
 # long arguments are implemented by putting a dash character followed by
 # a colon in the optspec, see trick by Arvid Requate at