revise mdsim/box to (almost) comply with H5MD v1.0

Note: writing string arrays as attributes is not yet implemented in
h5xx. This is needed for box/boundary.

- make reader/writer better configurable by revising the function
  interfaces to use keyword arguments. Location is no longer hard-wired
  to "observables/box".

- support output of box data that are either fixed in time or vary

- drop redundant Lua bindings for "edges" and "offset"
  These functions were bound both as property (to query the value) and
  as free functions (to yield a data slot) which was a source of
  potential confusion.

- add missing attribute "volume" in documentation

This commit refs #198804.
observables/phase_space: add box data to H5MD particles group

Currently, box data are written in the time-dependent format. For a
static box this leads to the repeated storage of the same edge and
offset data.

Whether the box changes in time or not depends on the user script and on
the integrator chosen (e.g., constant volume or constant pressure). A
possible robust solution would be to select upon creation of the box
whether it will change in time or not.

Adjust the continuation tests since "box/value" does not exist.

This commit refs #198804.
H5MD readers and writers: revise H5MD metadata

Comply with H5MD version 1.0.

Arrange metadata in subgroups, include optional author email.

Let readers::h5md::file::check() test for the presence and type of the
metadata.

Adjust unit test.

This commit refs #198804.
doc/faq: add note on linking error due to wrong Boost ABI