ikiwiki/doc/todo/support_linking_to_cgit.mdwn

As described on [Tails issue #5879](https://labs.riseup.net/code/issues/5879),
cgit wants URLs like:

        https://git-tails.immerda.ch/tails/commit/wiki/src/todo/fix_localized_iceweasel_search_engine.mdwn?id=c682a361418bef7bce040ea2905691d54be192ab

... while ikiwiki generates links like:

        https://git-tails.immerda.ch/tails/commit/wiki/src/todo%2Ffix_localized_iceweasel_search_engine.mdwn?id=c682a361418bef7bce040ea2905691d54be192ab

on the recentchanges page.

Would it make sense to add an option to skip URL-encoding when doing
the substitution of `\[[file]]` in `diffurl` and `historyurl`?

--[[intrigeri]]

> In `91b477c` I made a similar change to how the cvs backend encodes
> `diffurl`. Perhaps it applies to all VCS backends? --[[schmonz]]

>> Thanks a lot! I've not looked at it yet, but will try to do so
>> soonish, as this bug is a real problem for Tails when welcoming potential
>> new contributors. --[[intrigeri]]

>>> My `fix_diffurl_vs._cgit` branch now implements schmonz' change
>>> for the Git plugin. Please review and merge if you like
>>> it. --[[intrigeri]]

>>>> Ping? --[[intrigeri]]

>>>> Normally, my tendency towards pedantic preservation of existing APIs
>>>> would make me implement a new token \[[file_less_escaped]] or
>>>> something, analogous to `%s` vs. `%S` in [[shortcuts]]; but
>>>> gitweb and cgit are both OK with `/` not being escaped, whereas
>>>> only gitweb allows it to be escaped as `%2F`, so I think your
>>>> solution is fine. Also, it would need a much better name than
>>>> \[[file_less_escaped]], and I can't think of one.
>>>>
>>>> I don't have commit access to ikiwiki.info, but if I did,
>>>> [[I'd merge this|/users/smcv/yesplease]]. --[[smcv]]

[[wishlist]]

[[!tag patch]]