Route tokens containing slashes

[xfra35]

This is a followup of #214.

When defining a route like GET /explorer/@path: should encoded slashes be allowed inside @path or not?

E.g: /explorer/abc%2fdef.

Background:

• encoded slashes used to be treated as regular slashes in 2.x
• after https://github.com/bcosca/fatfree/issues/207, they were caught inside tokens
• after #71, they were treated as regular slashes again

We need to decide:

• either we make it clear that route tokens should never contain slashes
• or we replace the call to urldecode with something that would decode everything but slashes

Here are two suggestions for decoding UTF-8 characters while preserving encoded slashes:

// solution #1 (case sensitive)
$req=urldecode(str_replace(['%2f','%2F'],['%252f','%252F'],$this->hive['PATH']));

// solution #2 (case insensitive)
$req=implode('/',array_map(function($str){return str_replace('/','%2f',urldecode($str));},explode('/',$this->hive['PATH'])));

[bcosca]

Why not a configurable hive variable (like PASSTHRU) so we can maintain backward comptibility and at the same time allow the dev to make that decision to override default behavior?