/**

@page CHANGES-2-2 Version 2.2b

Version 2.2b (June 30, 2015)
----------------------------

Include all fixes in branch 2.1 indicated in \ref CHANGES-2-1 .

Changes from version 2.1 which are relevant for users:
- Changes leading to incompatible behavior:
  - Labels of quantities calculates by \ref SPRINT have changed from <i>label</i>.coord_<i>num</i> to <i>label</i>.coord-<i>num</i>
  - \ref METAD with WALKERS_MPI now writes a single hills file, without suffixes
  - removed the ./configure.sh script of v2.0.x, now plumed can only be configured using autotools (./configure)
  - \ref COM, \ref CENTER, and \ref GYRATION now automatically make molecules whole. In case you do not want them to do it, use NOPBC flag,
    which recovers plumed 2.1 behavior
  - Some MD code could now automatically trigger restart (e.g. gromacs when starting from cpt files). This can be overwritten using
    \ref RESTART NO.
  - Replica suffixes are now added by PLUMED *before* extension (e.g. use plumed.0.dat instead of plumed.dat.0)
  - When using \ref switchingfunction the STRETCH keyword is now implicit. NOSTRETCH is available to enforce the old behavior.
- Added partial OpenMP parallelization, see \ref Openmp
- Added multiple time step integration for bias potentials, see \ref MTS
- Link cells are now used in all multicolvars that involve \ref switchingfunction.  The link cell cutoff is
  set equal to 2.*\f$d_{\textrm{max}}\f$.  Where \f$d_{\textrm{max}}\f$ is the (user-specified) point at which
  the switching function goes to zero. Users should always set this parameter when using a switching function
  in order to achieve optimal performance.
- DHENERGY option is no longer possible within \ref DISTANCES.  You can still calculate the DHENERGY colvar by using \ref DHENERGY
- News in configure and install:
  - ./configure now allows external blas to be used with internal lapack. This is done automatically if only blas are available,
    and can be enforced with --disable-external-lapack.
  - ./configure supports --program-prefix, --program-suffix, and --program-transform-name.
  - make install supports DESTDIR and prefix.
  - Environment variables PLUMED_LIBSUFFIX and PLUMED_PREFIX are deprecated and will be removed in a later version.
- New actions
  - \ref DUMPMASSCHARGE to dump a file with mass and charges during MD.
  - \ref EFFECTIVE_ENERGY_DRIFT to check that plumed forces are not screwing the MD integrator.
  - \ref EXTENDED_LAGRANGIAN : in combination with  \ref METAD it implements metadynamics with Extended Lagrangian; standalone it implements TAMD/dAFED.
  - \ref DFSCLUSTERING calculate the size of clusters 
  - \ref DUMPMULTICOLVAR print out a multicolvar
  - \ref MFILTER_LESS filter multicolvar by the value of the colvar
  - \ref MFILTER_MORE 
  - \ref MFILTER_BETWEEN
  - \ref PCARMSD pca collective variables using OPTIMAL rmsd measure
  - \ref PCAVARS pca collective variables using any one of the measures in reference
  - \ref GRADIENT can be used to calculate the gradient of a quantity.  Used to drive nucleation
  - \ref CAVITY
  - \ref PUCKERING implemented for 5-membered rings (thanks to Alejandro Gil-Ley).
  - \ref WRAPAROUND to fix periodic boundary conditions.
- New features for existing actions:
  - Keywords UPDATE_FROM and UPDATE_UNTIL to limit update step in a defined time window, available only for actions where it would be useful.
  - Keyword UNNORMALIZED for \ref HISTOGRAM.
  - Keywords for \ref GROUP (REMOVE, SORT, UNIQUE) to allow more flexible editing of groups.
  - \ref DUMPATOMS now supports dumping xtc and trr files (requires xdrfile library).
  - \ref driver can now read xtc and trr files also with xdrfile library.
  - \ref driver accepts a --mc flag to read charges and masses from a file produced during
    molecular dynamics with \ref DUMPMASSCHARGE
  - Possibility to enable or disable \ref RESTART on a per action basis, available only for actions where it would be useful.
  - \ref MOLINFO now supports many more special names for rna and dna (thanks to Alejandro Gil-Ley).
  - VMEAN and VSUM allow one to calculate the sum of a set of vectors calculated by VectorMultiColvar.  Note these
  can also be used in tandem with \ref AROUND or \ref MFILTER_MORE to calculate the average vector within a particular
  part of the cell or the average vector amonst those that have a magnitude greater than some tolerance
  - New way of calculating the minimum value in multicolvars (ALT_MIN). This is less succetible to overflow for certain 
    values of \f$\beta\f$.  
  - New keywords for calculating the LOWEST and HIGHEST colvar calculated by a multicolvar
- Other changes:
  - File reader now supports dos newlines as well as files with no endline at the end.

For developers:

- In order to be able to use openmp parallelism within multcolvar, secondarystructure, manyrestraints and crystallisation
we had to make some substantial changes to the code that underlies these routines that is contained within vesselbase. In 
particular we needed to get rid of the derivatives and buffer private variables in the class ActionWithVessel.  As a consequence
the derivatives calculated in the various performTask methods are stored in an object of type MultiValue.  Within multicolvar
this is contained within an object of type AtomValuePack, which stores information on the atom indices.  If you have implemented
a new multicolvar it should be relatively straightforward to translate them so they can exploit this new version of the code.  Look 
at what has been done to the other multicolvars in there for guidance.  Sorry for any inconvenience caused.

*/
