hgweb: show obsolescence status of a commit As with phases, spartan theme shows a simple "obsolete: yes" on its own line (this allows replacing "yes" with something more useful in future, like output of obsfate* template functions). Everywhere else a new "tag" is added to the same line that has phase, branch, etc of a changeset; in gitweb and monoblue the element has gray background, in paper and coal the element is gray with a dashed underline.

context: add obsolete() method to basefilectx This method is now used in webutils.commonentry(), which adds common data items (commit hash, author, date, etc) for rendering changesets in hgweb. Usually, commonentry() is given a changectx as ctx; but in views related to files (e.g. file view, diff, annotate) it's replaced by a filectx, so the latter also needs to have obsolete() method.

check-code: grep's context flags don't need an extra space before number A bit of useless trivia found while researching this: OpenBSD's grep's -C has a default value (of 2) and disallows space before the argument (while -A and -B allow).

dirstate: make map implementation overridable Other implementations of dirstate will want to replace the class used for the dirstate map. Allow this to happen by making the class an attribute of the dirstate. Differential Revision: https://phab.mercurial-scm.org/D1347