Fix conversion of degree symbol "°"
* add handling of ">>", meaning much greater
* adapt ACID test 74 to test this
This however needs "parseStringsAsMath" to be "true", otherwise this fails, as described in issue #402.
Modify ACID test 74 decayingarmonic to include "much greater", "much smaller", "greater" and "smaller" ("<<", ">>", ">", "<") in the title to test handling of those characters.
Properly handle symbols "<", ">" (smaller, greater) if "parseStringsAsMath" is deactivated.
Handle possible tex error `double superscript` or `Missing {` for the strings `x^°` and `x_°` by proper escaping. Thanks go to @egeerardyn for pointing out the problematic case.
remove comment from test
Merge branch 'fix402'