Add undo support to muta->normal conversion

gui/fitCommands/guiMutaConvert.py

@@ -1,6 +1,5 @@
 import wx
 
-import eos.db
 import gui.mainFrame
 from gui import globalEvents as GE
 from service.fit import Fit
@@ -18,8 +17,13 @@ class GuiMutaConvertCommand(wx.Command):
         self.mutaplasmid = mutaplasmid
 
     def Do(self):
-        fit = eos.db.getFit(self.fitID)
+        sFit = Fit.getInstance()
+        fit = sFit.getFit(self.fitID)
         oldMod = fit.modules[self.position]
+        if oldMod.isEmpty:
+            return False
+        if oldMod.isMutated:
+            return False
 
         success = self.internal_history.Submit(FitReplaceModuleCommand(
             fitID=self.fitID,
@@ -33,7 +37,7 @@ class GuiMutaConvertCommand(wx.Command):
         if not success:
             return False
 
-        Fit.getInstance().recalc(self.fitID)
+        sFit.recalc(self.fitID)
         wx.PostEvent(self.mainFrame, GE.FitChanged(fitID=self.fitID))
         return True