adding simto/exact

[kohlhase]

I am trying to add similarity regions (see 3.{2,3} in https://gl.kwarc.info/mkohlhase/ntcadm-math/blob/master/topics/ntcir12/format/topicformat.pdf) into the NTCIR topic format. And I have come to the conclusion that it is best to add them to the the LaTeXML-MathWebSearch plugin. I made a new branch simto, which has the additions (grep for simto).

I tried to keep close to the qvar code, but it seems that in the postprocessing the

DefMathML('Apply:?:simto',

is never even executed (and I do not understand why). @dginev, could you please have a look?

[kohlhase]

I made a first test case, where I manually extended the "expected result". So the test will not really pass, but give some indication on what I want to see. Please excuse any copy/paste errors.