run-tests: add 'diff' entry in json report This patch adds to the json report the "diff" between expected and observed result. This diff can be useful for automatically filing bug report on failing tests.

bookmarks: make _readactive safe when readlines raises ENOENT When reading over static http, the file isn't actually opened until the readlines() call, so we have to check for ENOENT IOErrors here too. This is necessary so that we can use the bmstore everywhere for managing the active bookmark, which will be true in the next change.

wix: add help for current internal topics This makes the changes in a79cba6cb206 and 84784f834b3a available on Windows. I'm not setup to make the installer, so someone with experience in this area should probably give it a look. In looking around to try to figure out how to build the installer, it looks like the Makefile may need an update to $DOCFILES.