…e regexp (nicolas-grekas)

This PR was merged into the 4.1-dev branch.

Discussion
----------

 [Routing] Match 77.7x faster by compiling routes in one regexp

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Builds on top of #25961 and http://nikic.github.io/2014/02/18/Fast-request-routing-using-regular-expressions.html to make routing 77.7x faster (measured when matching the last dynamic route of 400 static + 400 dynamic routes.)

More benchs welcomed.

- [x] check static routes first in a switch
- [x] group same-modifiers regexps
- [x] put condition-less routes in a static map, in a switch's "default"
- [x] match host+pathinfo at the same time
- [x] group same-host regexps in sub-patterns
- [x] consider the host to move more static routes in the static switch
- [x] move static single-route "case" to "default" by adding requirements to $routes
- [x] group same-static-prefix in sub-patterns
- [x] group consecutive same-regex in a single "case"
- [x] move dynamic single-route "case" to "default" by adding requirements to $routes
- [x] extract host variables from the main match and remove the current 2nd match
- [x] extend same-prefix grouping to placeholders
- [x] group same-suffix hosts together

Here is my benchmarking code:

```php
<?php

namespace Symfony\Component\Routing;

require 'vendor/autoload.php';

$routes = new RouteCollection();

for ($i = 0; $i < 400; ++$i) {
    $routes->add('r'.$i, new Route('/abc'.$i));
    $routes->add('f'.$i, new Route('/abc{foo}/'.$i));
}

$dumper = new Matcher\Dumper\PhpMatcherDumper($routes);

eval('?'.'>'.$dumper->dump());

$router = new \ProjectUrlMatcher(new RequestContext());

$i = 10000;
$s = microtime(1);

while (--$i) {
    $router->match('/abcdef/399');
}

echo 'Symfony: ', 1000 * (microtime(1) - $s), "\n";

namespace FastRoute;

$dispatcher = simpleDispatcher(function(RouteCollector $r) {
    for ($i = 0; $i < 400; ++$i) {
        $r->addRoute('GET', '/abc'.$i, 'r'.$i);
        $r->addRoute('GET', '/abc{foo}/'.$i, 'f'.$i);
    }
});

$i = 10000;
$s = microtime(1);

while (--$i) {
    $dispatcher->dispatch('GET', '/abcdef/399');
}

echo 'FastRoute: ', 1000 * (microtime(1) - $s), "\n";
```

Commits
-------

f933f70 [Routing] Match 77.7x faster by compiling routes in one regexp