Add --ignore and --hide-deps options, both can be used multiple times.

These options are good to unclutter the graph:
--ignore completely ignore some module, useful with basic modules on which
lots of others depends, e.g. libc, libcutils, libutils.
--hide-deps doesn't render dependency links for some module, for example,
libpng depends on libz, but that's kinda obvious, can as well not show any
libpng dependencies to unclutter the view.