Remove code that prevented multiple instances

Author: ways2read

.vs/MathCATForPython/v17/.suo

@@ -0,0 +1,3 @@
+{
+  "CurrentProjectSetting": null
+}

.vs/ProjectSettings.json

@@ -4,7 +4,6 @@
 import os
 import sys
 import webbrowser  
-from tendo import singleton
 import gettext
 _ = gettext.gettext
 
@@ -173,12 +172,6 @@ def MathCATPreferencesDialogOnCharHook(self,event):
             UserInterface.OnClickOK(self,event)
         event.Skip()
 
-#if there is already an instance of MathCATPreferences running then terminate
-try:
-    me = singleton.SingleInstance() # will sys.exit(-1) if other instance is running
-except:
-    os.sys.exit(-2)
-
 app = wx.App(False)
 #get the default preferences (we don't write to this file)
 load_default_preferences()