assocs.extras: adding assoc-sift.
random.mersenne-twister: Don't use system-random-generator to initialize
Mersenne Twister. If there is no system random generator, startup can
fail.
vm: jit::jit is a c++ constructor but it does not allocate objects to the Factor heaps.
Add annotations for gc allocating.
html.parser.analyzer: when matching on classname, check that the tag has the given class