C++: Clarify units of a Token

This will avoid confusion when later more length and indices methods are
added.

In Token:
    length() --> bytes()
    begin() --> bytesBegin()
    end() --> bytesEnd()

Change-Id: I244c69b022e239ee762b4114559e707f93ff344f
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cpptools/doxygengenerator.cpp

@@ -83,7 +83,7 @@ QString DoxygenGenerator::generate(QTextCursor cursor)
         foreach (const Token &tk, tks) {
             if (tk.is(T_SEMICOLON) || tk.is(T_LBRACE)) {
                 // No need to continue beyond this, we might already have something meaningful.
-                cursor.setPosition(block.position() + tk.end(), QTextCursor::KeepAnchor);
+                cursor.setPosition(block.position() + tk.bytesEnd(), QTextCursor::KeepAnchor);
                 break;
             }
         }