GUI fixes

- do not show command result dialog when result is None
- apply fmtstr, if available

+ fix io import in secop.core
+ change old style <basecls>.__init__(self, ...) calls to super().__init__(...)

Change-Id: I599d5d8e8ff430ea9454a0858d703290e87454fc
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/26397
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Jens Krueger <jens.krueger@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/gui/params/__init__.py

@@ -39,7 +39,7 @@ class ParameterWidget(QWidget):
                  initvalue=None,
                  readonly=True,
                  parent=None):
-        super(ParameterWidget, self).__init__(parent)
+        super().__init__(parent)
         self._module = module
         self._paramcmd = paramcmd
         self._datatype = datatype
@@ -76,7 +76,12 @@ class GenericParameterWidget(ParameterWidget):
                                self.setLineEdit.text())
 
     def updateValue(self, value):
-        self.currentLineEdit.setText(str(value))
+        fmtstr = getattr(self._datatype, 'fmtstr', '%s')
+        if value.readerror:
+            value = str(value)
+        else:
+            value = fmtstr % (value.value,)
+        self.currentLineEdit.setText(value)
 
 
 class EnumParameterWidget(GenericParameterWidget):