remove mlabeledtr

[davidcarlisle]

As discussed in #72 and agreed in a MathmL WG call, this PR removes mlabeledr as well as the changes shown in this repository the schema has been modified to move mlabeledtr and the associated attributes to the legacy schema. See

w3c/mathml-schema@366fc8c

A HTML view is available at my fork github pages

mtr section

https://davidcarlisle.github.io/mathml/#presm_eqno

changes appendix

https://davidcarlisle.github.io/mathml/#chg_presm

schema
https://davidcarlisle.github.io/mathml/#parsing_rnc_legacy

[NSoiffer]

A few typos:

• "the first mtd represented the equation" -> "the first mtd represents the equation" (even when deprecated, it still represents it)
• "determined the placement" -> "determines the placement"
• "Un a CSS context," -> "In a CSS context,"

[davidcarlisle]

A few typos:

* "the first mtd represented the equation" -> "the first mtd represents the equation"  (even when deprecated, it still represents it)

done although (apart from the mathml-legacy schema it's not deprecated, but removed.)

* "determined the placement" -> "determines the placement"

as above

* "Un a CSS context," -> "In a CSS context,"

Done