corrections to combining characters table

[davidcarlisle]

The tables in appendix B3 show some entries with 3-digit hex such as U+02E and U+0B8 and (consequently) no comment with the unicode name as the id lookup failed. In one case the line is duplicated with both a broken entry for U+02E followed by the correct entry for U+002E full stop

This has been corrected in the source unicode.xml at commit

w3c/xml-entities@ed8b732

and the matching entries fixed here (by hand as I see no record of the script to generate combining-operators.html either here or in the xml-entities repo).

so there are no normative changes here just deleting one duplicated entry and replacing uncommented three-character hex by four character hex with a comment of the Unicode name.

[davidcarlisle]

Once the three invalid entries were corrected, the two tables in appendix B3 were identical apart from column order, this PR now deletes the second table, and places the columns in a different order so the "above/below" column acts as a row heading.

Also one extra paragraph of text added explaining the intent of the table.

as well as directly addressing #309 that B.3 is unclear this text could form the basis of addressing the long standing issue w3c/mathml#247

[davidcarlisle]

As agreed on the mathml-core call 26th Jan, I deleted the paragraph describing browser behavior for now,

So this just leaves the tables with corrected rows, and removing the table with re-ordered duplicate data.

The table has colums re-ordered to

<tr><th>Style</th><th colspan="2">Non Combining</th><th colspan="2">Combining</th></tr></thead><tbody>

where "style" could perhaps be renamed but a value above refers to use in mover or the relevant slot in munderover and similarly below refers to use in munder or the relevant slot in munderover,

I think this can be merged, with the paragraph deleted it is purely editorial re-arrangement of the table data.

[davidcarlisle]

meeting Feb 26 agreed to merge this