Deprecate proper name within translator's addition content style (char@style addpn)

[klassenjm]

Proposal

• Deprecate addpn from the supported @style attributes list for <char>.

Note: Deprecating does not remove the @style attribute values from the USX schema, but its use is strongly discouraged.

This is the USX companion to USFM 3.0 proposal "Deprecate combined marker for proper name within translator's addition (\addpn …\addpn*)". See: ubsicap/usfm#20 for detail.

This markup can be properly represented by nested <char> elements.

Example

<char style="add">... <char style="pn">...</char> ...</char>

[klassenjm]

No documentation changes for 3.0 -- addpn was never included in earlier documentation.