manifestv2: add support for writing new manifest format If .hg/requires has 'manifestv2', the manifest will be written using the new format.

manifestv2: add support for reading new manifest format The new manifest format is designed to be smaller, in particular to produce smaller deltas. It stores hashes in binary and puts the hash on a new line (for smaller deltas). It also uses stem compression to save space for long paths. The format has room for metadata, but that's there only for future-proofing. The parser thus accepts any metadata and throws it away. For more information, see http://mercurial.selenic.com/wiki/ManifestV2Plan. The current manifest format doesn't allow an empty filename, so we use an empty filename on the first line to tell a manifest of the new format from the old. Since we still never write manifests in the new format, the added code is unused, but it is tested by test-manifest.py.

manifestv2: set requires at repo creation time While it should be safe to switch to the new manifest format on an existing repo, let's keep it simple for now and make the configuration have any effect only at repo creation time. If the configuration is enabled then (at repo creation), we add an entry to requires and read that instead of the configuration from then on.

test-manifest: extract constants for binary hashes The binary hashes are used quite frequently, so let's extract constants for them so we don't have to repeat binascii.unhexlify() so often.

test-manifest: create constant for empty manifest For symmetry with manifest v2, once we add that, let's extract a constant for the empty v1 manifest.

patchbomb: factor out scmutil.revrange() calls This allows us to access the calculated revs in patchbomb() function.

patchbomb: return outgoing revs as a smartset This helps to factor out scmutil.revrange() calls from _getpatches() and _getoutgoing(). In future patches, a smartset will be passed to _getpatches().

templatefilters: add "upper" and "lower" for case conversion Typically it will be used in patchbomb's flag template, which will be implemented by future patches.

repoview: improve compute staticblockers perf Previously we would compute the repoview's static blockers by finding all the children of hidden commits that were not hidden. This was O(number of commits since first hidden change) since 'children' requires walking every commit from tip until the first hidden change. The new algorithm walks all heads down until it sees a public commit. This makes the computation O(number of draft) commits, which is much faster in large repositories with a large number of commits and a low number of drafts. On a large repo with 1000+ obsolete markers and the earliest draft commit around tip~200000, this improves computehidden perf by 200x (2s to 0.01s).

hgweb: add phase to {changeset} template It's pretty surprising phase wasn't part of this template call already. We now expose {phase} to the {changeset} template and we expose this data to JSON. This brings JSON output in line with the output from `hg log -Tjson`. The lone exception is hweb doesn't print the numeric rev. As has been stated previously, I don't believe hgweb should be exposing these unstable identifiers. (We can add them later if we really want them.) There is still work to bring hgweb in parity with --verbose and --debug output from the CLI.