Remove unused wxQT panel header and implementation
Fix client data (missing dtor) memory leak in wxQT
Remove superflous wxQtPointer helper (and header)

Note that this added a new level of ref counting and the automatic deletion was causing premature destuction of Qt control's children.
Direct destruction of the QObject is even discouraged and can cause chash according Qt docs, so deleteLater() is safer.
For more info see QObject::~QObject comments (Qt source)