manifest: break mancache into two caches The old manifest cache cached both the inmemory representation and the raw text. As part of the manifest refactor we want to separate the storage format from the in memory representation, so let's split this cache into two caches. This will let other manifest implementations participate in the in memory cache, while allowing the revlog based implementations to still depend on the full text caching where necessary.

dispatch: explicitly pass fancyopts optional arg as a keyword I've been baffled by this a couple of times (mainly wondering if any callers of fancyopts.fancyopts that don't use gnu=True exist), so let's just specify this as a keyword argument to preserve sanity.