configure:
- added intel compilers to the list of standard compilers
- added a check that stops the configuration if --enable-almost is set but almost is not found
configure:
- if enable-gsl is used and gsl are not found stops with error
- give a warning if a default ON option cannot be activated
configure:
- it says if plumed will be compiled with MPI or not
Merge branch 'v2.1'