Center all QAbstractSpinBox, not just integer QSpinBox

Fixes misaligned QDoubleSpinBox, and aligns QDateTimeEdit (which may be
a good thing as well).

Fixes #12.

kstyle/breezestyle.cpp

@@ -22,6 +22,7 @@
 #include <KColorUtils>
 #include <KIconLoader>
 
+#include <QAbstractSpinBox>
 #include <QApplication>
 #include <QBitmap>
 #include <QCheckBox>
@@ -40,7 +41,6 @@
 #include <QRadioButton>
 #include <QScrollBar>
 #include <QItemDelegate>
-#include <QSpinBox>
 #include <QSplitterHandle>
 #include <QTextEdit>
 #include <QToolBar>
@@ -419,7 +419,7 @@ namespace Breeze
             widget->setAttribute(Qt::WA_StyledBackground);
         } else if ( auto btn = qobject_cast<QPushButton*> (widget) ) {
             btn->setAutoDefault(false);
-        } else if ( auto spbx = qobject_cast<QSpinBox*> (widget) ) {
+        } else if ( auto spbx = qobject_cast<QAbstractSpinBox*> (widget) ) {
             spbx->setAlignment(Qt::AlignCenter);
         }