Treat CONTENT attribute not only from String elements (but others as well)

[wrznr]

Currently, only CONTENT attributes from String are evaluated and realized in the resulting TEI. But ALTO has some other elements which may carry this attribute, most notably HYP.

[bertsky]

Isn't it also debatable whether it is correct to just join all TextLine/String like so?

mets-mods2tei/mets_mods2tei/api/alto.py

Line 95 in fc7b0f7

return " ".join(element.get("CONTENT") for element in line.xpath("./alto:String", namespaces=ns))

(I would expect that the white-space joiner only be applied where there is an SP interspersed. But there might be different conventions in the field, like having no SP at all, i.e. implicit white-space, as in PAGE-XML.)

[bertsky]

Regarding HYP itself, I'm not sure anymore whether printing @CONTENT verbatim is correct: Basisformat states that only hyphen-minus should be allowed.

Maybe make that a config parameter? (We could technically have lots of these; related to #26)