Optimize the namespaces analyzer

Instead of looping on all tokens, even inside the namespace it identified,
the analyzer now continues the analysis after the end of the identified
namespace, thanks to the fact that namespaces cannot be nested.

src/Tokenizer/Analyzer/NamespacesAnalyzer.php

@@ -29,7 +29,9 @@ public function getDeclarations(Tokens $tokens)
     {
         $namespaces = [];
 
-        foreach ($tokens as $index => $token) {
+        for ($index = 1, $count = \count($tokens); $index < $count; ++$index) {
+            $token = $tokens[$index];
+
             if (!$token->isGivenKind(T_NAMESPACE)) {
                 continue;
             }
@@ -57,6 +59,9 @@ public function getDeclarations(Tokens $tokens)
                 $index,
                 $scopeEndIndex
             );
+
+            // Continue the analysis after the end of this namespace to find the next one
+            $index = $scopeEndIndex;
         }
 
         if (0 === count($namespaces)) {