It now takes paths into account correctly

This makes it possible to use the command

port test plumed

to compile and test plumed.

Notice that tests on travis are still performed explicitly,
I plan to fix this in the near future, after having verified that there
are no problems with timings.

Minor changes to VES manual

cc @valsson

See https://groups.google.com/d/msgid/plumed-users/8fcca53b-38d1-470e-a413-a4339702c6db%40googlegroups.com

Thanks to Qingh Liao

cc @HanatoK I fixed the problem. Namely, plumed was linking by mistake
another boost version (homebrew).

HomeBrew boost was linked by mistake.

osx8.2 is deprecated.

I think it is better NOT to recommend sourcing "sourceme.sh". Most users
should install plumed with the canonical procedure (make install)

Notice that this breaks previous "check" target, that I think
was anyway useless.

check: does the check with the non-installed plumed
installedcheck: does the check with the installed plumed

In case MPIEXEC was passed at configure time, it is used.
In case not, env var PLUMED_MPIRUN is checked (for backward compatibility).
Otherwise, `mpirun` is used.

Can be retrieved with

plumed config mpiexec

Added patch for QE 6.2

Problem was likely due to an upgrade of mpi in homebrew on travis

cc: @ralf-meyer

Minor fixes of eABF module