Updates to .NET 4.5 cause exception to be thrown when saving settings

[jimradford]

As of commit 836d540 when you try to make a change to settings in Tools->Options clicking save throws an exception:

System.Configuration.SettingsPropertyNotFoundException
HResult=0x80131500
Message=The settings property 'Action_RenameTab_Shortcut' was not found.
Source=System
StackTrace:
at System.Configuration.SettingsBase.GetPropertyValueByName(String propertyName)
at System.Configuration.SettingsBase.get_Item(String propertyName)
at System.Configuration.ApplicationSettingsBase.GetPropertyValue(String propertyName)
at System.Configuration.ApplicationSettingsBase.get_Item(String propertyName)
at SuperPutty.Properties.Settings.SettingChangingEventHandler(Object sender, SettingChangingEventArgs e) in J:\OneDrive\Dev\GitRepos\New folder\SuperPutty\Properties\Settings.cs:line 44
at System.Configuration.ApplicationSettingsBase.OnSettingChanging(Object sender, SettingChangingEventArgs e)
at System.Configuration.ApplicationSettingsBase.set_Item(String propertyName, Object value)
at SuperPutty.Properties.Settings.UpdateFromShortcuts(KeyboardShortcut[] shortcuts) in J:\OneDrive\Dev\GitRepos\New folder\SuperPutty\Properties\Settings.cs:line 120
at SuperPutty.dlgFindPutty.buttonOk_Click(Object sender, EventArgs e) in J:\OneDrive\Dev\GitRepos\New folder\SuperPutty\dlgFindPutty.cs:line 370
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)