Speed up Theme Option Page load

Fixes #1245

The CheckChanged event was causing load settings to be called more than once on form load.

mRemoteV1/UI/Forms/OptionsPages/ThemePage.cs

@@ -3,7 +3,6 @@ using System.Windows.Forms;
 using mRemoteNG.Themes;
 using System.Linq;
 using System.Collections.Generic;
-using System.Drawing;
 using BrightIdeasSoftware;
 using mRemoteNG.UI.Forms.Input;
 
@@ -56,6 +55,7 @@ namespace mRemoteNG.UI.Forms.OptionsPages
 
         public override void LoadSettings()
         {
+            themeEnableCombo.CheckedChanged -= themeEnableCombo_CheckedChanged;
             base.SaveSettings();
             //At first we cannot create or delete themes, depends later on the type of selected theme
             btnThemeNew.Enabled = false;
@@ -81,6 +81,7 @@ namespace mRemoteNG.UI.Forms.OptionsPages
                 // reset to the default theme when disabling theme support
                 _themeManager.ActiveTheme = _themeManager.DefaultTheme;
             }
+            themeEnableCombo.CheckedChanged += themeEnableCombo_CheckedChanged;
         }
 
         private void ListPalette_FormatCell(object sender, FormatCellEventArgs e)