more SDL2-related backports from sauer

* use keyrepeat and textinput switch code from sauer (on windows, opening
  a console with "t" also produced a "t" as text otherwise)
* screenw and screenh are now cubescript-variables that always reflect
  the actual resolution of the screen or the window

DOCREF screenw screenh

source/src/editing.cpp

@@ -54,7 +54,7 @@ void toggleedit(bool force)
         //put call to clear/restart gamemode
         player1->attacking = false;
     }
-    keyrepeat = editmode;
+    keyrepeat(editmode, KR_EDITMODE);
     editing = editmode ? 1 : 0;
     editing_sp = editmode && !multiplayer(NULL) ? 1 : 0;
     player1->state = editing ? CS_EDITING : (watchingdemo ? CS_SPECTATE : CS_ALIVE);