obsolete: introduce an `_enabled` switch to disable the feature by default Obsolete markers wide-usage and propagation should be avoided by default until the obsolete feature is more mature. This changeset introduce the `_enable` variable and prevent the creation of obsolete marker if the feature is set to `False` (the default). More limitation comes in followup changesets.

pushkey: splits obsolete marker exchange into multiple keys Obsolete markers are now exchanged in smaller pieces that fit in a http header. This changes is done to avoid 400 bad request error when exchanging obsolete puskey over http. The last key pushed is always hold by the "dump0" key to ensure an easy place to hook for people who need it.

obsolete: add debug output regarding obsolete marker exchange.

pushkey: add more verbose debug output regarding pushkey Very few data are displayed now, making it hard to debug phases and obsolete related issues.

debugobsolete: do not traceback on invalid node identifiers

revset: minor doc fixes on obsolete related revsets

hgweb: make paper:error consistent with template Tests fixed by Patrick Mézard <patrick@mezard.eu>

hgweb: avoid traceback when file or node parameters are missing Previously, browsing to http://serv/diff would generate an internal server error due to the file and node parameters being missing. The same error also occurred for filelog, comparison and annotate.

hgweb: fix "branches" links in gitweb template Tests fixed by Patrick Mézard <patrick@mezard.eu>

hgweb: fix typo in monoblue template