Merge branch 'master' into new-neighbor

doc/src/PDF/colvars-refman-lammps.pdf

doc/src/fix_colvars.txt

examples/cmap/charmm22.cmap

examples/tad/README

lib/colvars/colvar.cpp

lib/colvars/colvar.h

lib/colvars/colvarbias_histogram.cpp

lib/colvars/colvarbias_meta.cpp

lib/colvars/colvarbias_restraint.cpp

lib/colvars/colvarbias_restraint.h

lib/colvars/colvarcomp.cpp

lib/colvars/colvarcomp.h

lib/colvars/colvarcomp_angles.cpp

lib/colvars/colvarcomp_coordnums.cpp

lib/colvars/colvarcomp_distances.cpp

lib/colvars/colvardeps.cpp

lib/colvars/colvardeps.h

lib/colvars/colvargrid.h

lib/colvars/colvarmodule.cpp

lib/colvars/colvarmodule.h