Moved plumed-* scripts except plumed-patch

Now when plumed is installed the scripts are placed in
lib/plumed/
instead of
bin/

This makes it more robust the installation of several versions with suffixes

I only left in place the script "plumed-patch" which is likely
the most used.

I added plenty of messages at the end of ./configure and make install
+ I explained it in the user doc