fix problems with formatted texts so that they do not have to contain 0 byte anymore

TextFeld.cpp

@@ -613,7 +613,7 @@ void TextFeld::setFormattedText(const char* txt)
             tm->textStyle.add(current);
             break;
         case 6:
-            current.rendererIndex = (unsigned char)txt[++i];
+            current.rendererIndex = (unsigned char)(txt[++i] - 1);
             tm->textStyle.add(current);
             break;
         case 7: