Introduced a token cache for the C++ editor.

This should speed things up a bit, because before, the line was tokenized at
least 3 times.

src/libs/cplusplus/MatchingText.h

@@ -35,11 +35,12 @@
 namespace CPlusPlus {
 
 class BackwardsScanner;
+class TokenCache;
 
 class CPLUSPLUS_EXPORT MatchingText
 {
 public:
-    MatchingText();
+    MatchingText(TokenCache *tokenCache);
 
     static bool shouldInsertMatchingText(const QTextCursor &tc);
     static bool shouldInsertMatchingText(const QChar &lookAhead);
@@ -50,6 +51,8 @@ public:
 
 private:
     bool shouldInsertNewline(const QTextCursor &tc) const;
+
+    TokenCache *_tokenCache;
 };
 
 } // end of namespace CPlusPlus