Normalize letter cases in URL

[mik-jozef]

What problem does this feature solve?

If the user visits the URL /path/example/view, and a route /Path/Example/mode(View|Edit) is registered in the router, and router uses case insensitive matching, (and maybe if a flag is set on the route/globally), router should replace the current URL with /Path/Example/View.

Why: to have the best of both case sensitive and insensitive matching - a canonical URL for a single resource, users won't have to remember letter cases, and aesthetic preference of /Path/Example/View to /pAtH/eXaMpLe/ViEw.

What does the proposed API look like?

If this should be behind a flag, I see two ways to do that:

0. A new boolean option, eg. normalizeLetterCases in RouteConfig interface, or
1. Since 0. would be non-orthogonal with the caseSensitive option, they could be merged into a single letterCase option of type 'strict'|'normalize'|'ignore'

[posva]

Unfortunately, there are quite a few edge cases we wouldn't be able to handle like properly changing params or being inflexible by always forcing an option and this being a very specific need that can be solved in user land by doing the needed string manipulation in an afterEach + replace, I would rather keep it that way