templatefilters: make json filter be byte-transparent (BC) (issue4926) This is necessary to preserve filename encoding over JSON. Instead, this patch inserts "|utf8" where non-ascii local-encoding texts can be passed to "|json". See also the commit that introduced "utf8" filter.

hgweb: add option to convert encoding of graphdata() Because future patches will change "|json" filter to handle input bytes transparently, i.e. use UTF-8b encoding, "{jsdata}" must keep data in UTF-8 bytes, whereas "{nodes}" are text. This patch inserts encodestr() where localstr is likely to survive.

hgweb: remove unused argument from graphdata() factory As graphdata() is wrapped by lambda, there's no reason to pass unused arguments to it.

templatefilters: add "utf8" to get utf-8 bytes from local-encoding text This will be applied prior to "|json" filter. This sounds like odd, but it is necessary to handle local-encoding text as well as raw filename bytes. Because filenames are bytes in Mercurial and Unix world, {filename|json} should preserve the original byte sequence, which implies {x|json} -> '"' toutf8b(x) '"' On the other hand, most template strings are in local encoding. Because "|json" filter have to be byte-transparent to filenames, we need something to annotate an input as a local string, that's what "|utf8" will do. {x|utf8|json} -> '"' toutf8b(fromlocal(x)) '"' "|utf8" is an explicit call, so aborts if input bytes can't be converted to UTF-8.

templatefilters: drop broken "jsonescape" from filters table (BC) It's been unused, undocumented and flawed in that it expects a unicode input, never works correctly if an input has non-ascii character. We should use "json" filter instead.

treemanifest: rewrite text() using iterentries() This simplifies a bit. Note that the function is only used when manually testing with _treeinmem=True.