Make linear optimization the new default (JYU-IBA#193)

- this should be better than NSGA-II now
- opening the optimization dialog causes a brief flash now for some
  reason, probably related to the order of operations, or maybe the
  choose_optimization_method call

dialogs/simulation/optimization.py

@@ -151,17 +151,20 @@ def __init__(self, simulation: Simulation, parent):
 
  self.method_radios.addButton(self.nsgaiiRadioButton)
  self.method_radios.addButton(self.linearRadioButton)
+ self.linearRadioButton.setChecked(True)
 
  self.mode_radios = QtWidgets.QButtonGroup(self)
  self.mode_radios.buttonToggled[QtWidgets.QAbstractButton, bool].connect(
  self.choose_optimization_mode)
  self.parametersLayout.addWidget(self.nsgaii_recoil_widget)
  self.parametersLayout.addWidget(self.nsgaii_fluence_widget)
+ self.nsgaii_recoil_widget.hide()
  self.nsgaii_fluence_widget.hide()
 
+ # TODO: Why does selecting linear_recoil_widget by default cause a
+ # brief flash when opening the optimization dialog?
  self.parametersLayout.addWidget(self.linear_recoil_widget)
  self.parametersLayout.addWidget(self.linear_fluence_widget)
- self.linear_recoil_widget.hide()
  self.linear_fluence_widget.hide()
 
  self.mode_radios.addButton(self.fluenceRadioButton)