Polish and fix wx.lib.masked.textctrl module

Please check at the very end of the modified file where wx.PreTextCtrl() was fixed to wx.TextCtrl() and wx.PostCreate() was fixed to wx.Create().

Phoenix does not have wx.PreXxx stuff, so I fixed this (someone didn't fully port this module to Phoenix). Not sure about the PostCreate() if it is just Create() now in Phoenix. The 'Classic versus Phoenix' document does not document PostCreate().

Oh, I hope you like what I did.