templatekw: allow the caller of showlist() to specify the join() separator The keyword {latesttag} currently manually joins the list of tags using ':', which prevents a transparent switch over to a hybrid list.

archive: use {changessincelatesttag} to build the metadata file This isolates the current magic when dealing with wdir() and only().

templatekw: introduce the changessincelatesttag keyword Archive is putting a value with the same name in the metadata file, to count all of the changes not covered by the latest tag, instead of just along the longest path. It seems that this would be useful to have on the command line as well. It might be nice for the name to start with 'latesttag' so that it is grouped with the other tag keywords, but I can't think of a better name. The initial version of this counted a clean wdir() and '.' as the same value, and a dirty wdir() as the same value after it is committed. Yuya objected on the grounds of consistency [1]. Since revsets can be used to conditionally select a dirty wdir() or '.' when clean, I can build the version string I need and will defer to him on this. [1] https://www.selenic.com/pipermail/mercurial-devel/2015-June/071588.html

help: support 'hg help template.somekeyword' Previously the output was simply 'abort: help section not found'.