Further work on getting alt codes working

More testing required, but SDL_iconv_utf8_ucs4() seems to do the trick!

src/i_video.c

@@ -559,7 +559,7 @@ static void I_GetEvent(void)
             case SDL_TEXTINPUT:
             {
                 ev.type = ev_textinput;
-                ev.data1 = Event->text.text[strlen(Event->text.text) - 1];
+                ev.data1 = ((char *)SDL_iconv_utf8_ucs4(Event->text.text))[0];
                 D_PostEvent(&ev);
                 break;
             }