Make `public` certain documented functions

[JeffFessler]

According to the history file, in v0.14 a bunch of methods were unexported and require the HDF5 module prefix, which is fine. See list below.
Nevertheless, should these methods all be declared public so that developers can rely on them?

The one I care about the most is readmmap and that one is described in the docs which certainly seems to imply it is public
I am unsure which of the rest of this list should be considered public (and hence stable).

file
filename
name
get_chunk
get_datasets
iscontiguous
ishdf5
ismmappable
root
readmmap
set_dims!
get_access_properties
get_create_properties
create_external_dataset

[mkitti]

Thank you for the list. We have not used the public keyword extensively yet, but this might be a good starting point

Would you like to submit a pull request?

[JeffFessler]

Sure - see #1217 as a starting point. Thanks.

[JeffFessler]

closed by #1217