TITANIC: Memory leaks in DirectDrawManager

[csnover]

valgrind reports from dafioram

==16727== 1,228,912 (16 direct, 1,228,896 indirect) bytes in 1 blocks are definitely lost in loss record 2,662 of 2,668
==16727==    at 0x4C2E19F: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==16727==    by 0x366A9B: Titanic::DirectDrawManager::initFullScreen() (direct_draw.cpp:86)
==16727==    by 0x3669F4: Titanic::DirectDrawManager::initVideo(int, int, int, int) (direct_draw.cpp:75)
==16727==    by 0x328907: Titanic::OSScreenManager::setMode(int, int, int, unsigned int, bool) (screen_manager.cpp:103)
==16727==    by 0x347888: Titanic::CMainGameWindow::applicationStarting() (main_game_window.cpp:58)
==16727==    by 0x211585: Titanic::TitanicEngine::initialize() (titanic.cpp:125)
==16727==    by 0x211709: Titanic::TitanicEngine::run() (titanic.cpp:152)
==16727==    by 0x1FC228: runGame(PluginSubclass<MetaEngine> const*, OSystem&, Common::String const&) (main.cpp:263)
==16727==    by 0x1FD447: scummvm_main (main.cpp:529)
==16727==    by 0x1FA325: main (posix-main.cpp:45)
==16727==