Clean up the clean up of the typed answer.

Clean up the clean up of the typed answer. Like this typing “<” &c. when the card contains “&lt;” (which was originally typed as “<” as well) should work, as well as “\”s.

This is the third try. Improvement over the first: fix conflict in whitespace clean up, over the second: clean up `[` only to avoid `[sound:`s, also make `\`s work, that is, show up.

Is this consistent with Anki Desktop?