manifest: allow specifying the revlog filename Previously we had hardcoded the manifest filename to be 00manifest.i. In our external treemanifest extension, we want to allow writing a treemanifest side by side with a flat manifest, so we need to be able to store the root revisions at a different location (in our extension we use 00manifesttree.i). This patches moves the revlog name to a parameter so we can adjust it.