- [FIX] clip(x,y,w,h) works as expected.

- [NEW] clip() with no arguments resets clipping region.
- [FIX] cls() respects clipping region (but now it's slower)
- [FIX] pset's and pget now respect clipping region correctly

lua.cpp

@@ -259,11 +259,15 @@ extern "C" {
     }
 
     static int cpp_clip(lua_State *L) {
-        int x = luaL_checknumber(L, 1);
-        int y = luaL_checknumber(L, 2);
-        int w = luaL_checknumber(L, 3);
-        int h = luaL_checknumber(L, 4);
-        clip(x, y, w, h);
+        if (lua_gettop(L) == 0) {
+            clip();
+        } else {
+            int x = luaL_checknumber(L, 1);
+            int y = luaL_checknumber(L, 2);
+            int w = luaL_checknumber(L, 3);
+            int h = luaL_checknumber(L, 4);
+            clip(x, y, w, h);
+        }
         return 0;
     }