QStringBuilder

This was done in https:/fluxer/katie/commit/5863f7dd623cffea75f51a63cf33472b09f18d9f, the % operator is ambiguous now. You can make use of it, as it was ment to be, conditionally if QT_USE_FAST_OPERATOR_PLUS or QT_USE_QSTRINGBUILDER are defined at pre-processor level.

No source compatible methods are in place because you should evaluate how to handle this in your projects. For an example:

QString mystring = QString("123") % QString("456");

Should be changed to:

QString mystring = QString("123") + QString("456");