Deprecate pronunciation info marker (\pro ...\pro*) in favour of ruby annotations proposal

[klassenjm]

Proposal

• Deprecate the existing pronunciation marker \pro ...\pro*. Promote the alternative Ruby annotations markup \rb ...\rb* and \rt ...\rt*. See Syntax for applying ruby annotations (CJK texts) (add \rb ...\rb*) #31

A companion USX 3.0 proposal exists at: ubsicap/usx#25

Details

The existing pronunciation marker \pro ...\pro* has been used primarily (perhaps exclusively?) in Taiwanese Chinese texts to mark Zhi-Yin/Pin-Yin annotation text. Zhi-Yin markup for these Chinese texts is always on the righthand side and for each individual ideogram (and written top-down). For this reason, only a single character marker has been required, since the Zhi-Yin is not being associated with variable length string of preceding characters. Example: For 北京 ("Beijing") the existing markup would be 北\pro ㄅㄟˇ\pro*京\pro ㄐ一ㄥ\pro*

In some other CJK texts, annotations are not necessarily associated to only one character at a time. In an example Japanese text (Biblica) there are up to six base characters associated with a string of up to 13 annotation characters. In this case we could not properly identify the texts without marking both the base and annotation characters.

Since USFM 3.0 proposes to add a new pair of marker for Ruby annotations, the current \pro ...\pro* marker become redundant.