marked.js has an infuriating bug that even when "github flavored markdown" is

turned on, it has problems with underscores in the middle of words. Worse, it

didn't handle escaped underscores in the middle of hyperlinks, so even when

they were escaped, it was broken in some cases.
This change pulls in a version of marked.js from an open pull request that

fixes these bugs, which means that we no longer have to escape them.

Ran unit tests
Posted some changes with underscores mid-word, saw that the escaping was gone

  and that all text looked correct (with no unexpected em or strong).