* Add analytics munger w/ munge heading * More link autofixes * Allow running a subset of munges * Fix repo root detection * Only process non-preformatted blocks * Gendocs no longer adds the analytics link; mungedocs does that in a second pass.
Rather than terminating, Collect the errors and print them per-file-per-munge.
Links that don't work yet can be prefixed with "TODO:" to avoid the check.
