[h5md-user] Time (in)dependent data

[Pierre de Buyl]

Still as a followup to the meeting in Stuttgart:

A proposal is made to work in the following way: at any place in the file, a
data (such as /trajectory/protein/position) may be either:
- A dataset (with shape [N]). It does not depend on time.
- A H5MD time-dependent conforming group (see current spec).

The idea is that this change would apply also for the box and for "species" and
"mass" where special cases are now in place.

All in all, this seems to clarify things a lot but it would be wise to give us
some (limited amount of time indeed, so as not to delay further H5MD 1.0) time
to evaluate the impact on H5MD writers and readers.

Cheers,

Pierre