default module name resolver: fix cache

The cache was keyed on `current-library-collection-paths`, but
not other parameters such as `current-library-collection-links`,
so it was too "sticky" in the case that some parameters changed.
Adjust the cache to be specific to loaded module in a namespace's
module registry.
scribble/base: add `#:style` argument to `image`
scribble docs: fix example for `literal`