Change up/down increment in UI to 0.001 BTC (issue #760)

src/qt/bitcoinamountfield.cpp

@@ -22,6 +22,7 @@ BitcoinAmountField::BitcoinAmountField(QWidget *parent):
     amount->setDecimals(8);
     amount->installEventFilter(this);
     amount->setMaximumWidth(170);
+    amount->setSingleStep(0.001);
 
     QHBoxLayout *layout = new QHBoxLayout(this);
     layout->addWidget(amount);