feat($core): redirects for clean urls

[ulivz]

Summary

In VuePress, we have following convention about routing:

• /foo/ means source file is /foo/{README|index}.md
• /foo.html means your source file is /foo.md

The original design of VuePress relied on above two styles
of routing, especially the calculation involved of routes at
// default theme. so we can't easily modify /foo.html directly
to /foo (i.e. remove html suffix)

This utility handles redirect of clean urls, with this utility, you'll
get:

For unknown request /foo

• redirect to /foo.html if it exists
• redirect to /foo/ if it exists

For unknown request /foo/

• redirect to /foo.html if it exists

If all the above redirect rules don't exist, you'll get a 404

---

Note that this PR doesn't provide you the ability to remove the
html suffix at the route level, it just allows you to use clean urls.

cc @octref

---

Related: #603
Related: #608
Related: #1060
Close: #720
Close: #931

[awulkan]

If I understood this correctly, the routes will still end in .html? Or am I wrong?

[ulivz]

I have noted it in the description:

Note that this PR doesn't provide you the ability to remove the
html suffix at the route level, it just allows you to use clean urls.

FYI, we don't plan to support removing the html suffix for now(1.x)

[awulkan]

FYI, we don't plan to support removing the html suffix for now(1.x)

Oh, so that won't happen until 2.x? Which might not happen for a LONG time. :'(

I guess I'll use another static site generator for now then, because I can't afford losing search engine rankings when switching URL structure.

[shigma]

@awulkan

Now you can use plugin-clean-urls if you want your urls to be /foo/ or even /foo instead of /foo.html.

[nelson6e65]

OMG! Amazing, @shigma

[awulkan]

@shigma Well done. :)

[ulivz]

Just selected a wrong review target...