Added virtual to UIWindow destructor
Added virtual to UIWindow destructor

Fixes issue #198. See http://stackoverflow.com/questions/461203/when-to-use-virtual-destructors

sshaileshk/Polycode,ivansafrin/Polycode,thorsummoner/polycode,hksonngan/Polycode,Xetlin/Lua,mcanthony/Polycode,carlosmarti/Polycode,Xetlin/Lua,sshaileshk/Polycode,GovanifY/Polycode,zeebok/Polycode,carlosmarti/Polycode,fodinabor/Polycode,Xetlin/Lua,ivansafrin/Polycode,GovanifY/Polycode,zeebok/Polycode,GovanifY/Polycode,cartman300/Polycode,mcanthony/Polycode,carlosmarti/Polycode,mcanthony/Polycode,hksonngan/Polycode,fodinabor/Polycode,thorsummoner/polycode,zeebok/Polycode,Xetlin/Lua,sshaileshk/Polycode,ivansafrin/Polycode,cartman300/Polycode,GovanifY/Polycode,thorsummoner/polycode,fodinabor/Polycode,thorsummoner/polycode,hksonngan/Polycode,hksonngan/Polycode,mcanthony/Polycode,sshaileshk/Polycode,fodinabor/Polycode,cartman300/Polycode,ivansafrin/Polycode,zeebok/Polycode,cartman300/Polycode