First compilation and test of procedure `get_snapshot`. Change order
of dummy arguments of procedure `get_snapshot`: make it more
convenient for call with keywords. Replace dummy arguments periodic
and `dist_lim` by dummy argument copy. Add dummy arguments
`ishape_last` and k1. Promote `hshp_extremum`, `hshp_outermost`,
`hshp_max_speed` from local variables to dummy arguments.

In program `test_read_snapshot`, read input SHP triplet from command
line instead of requiring it to be present in the current directory
with the name `SHP_triplet_old`.

Remove directory `Tests/Input/Region_1/SHP_triplet`, which was not used.