Fix polygon drawing: index of coordinates was off by one.

--HG--
branch : minor

src/modules/graphics/opengl/Graphics.cpp

@@ -914,7 +914,7 @@ namespace opengl
 			glDisable(GL_TEXTURE_2D);
 			glEnableClientState(GL_VERTEX_ARRAY);
 			glVertexPointer(2, GL_FLOAT, 0, (const GLvoid*)coords);
-			glDrawArrays(GL_POLYGON, 0, count / 2); // opengl will close the polygon for us
+			glDrawArrays(GL_POLYGON, 0, count/2-1); // opengl will close the polygon for us
 			glDisableClientState(GL_VERTEX_ARRAY);
 			glEnable(GL_TEXTURE_2D);
 		}

src/modules/graphics/opengl/wrap_Graphics.cpp

@@ -901,7 +901,7 @@ namespace opengl
 			}
 		} else {
 			for (int i = 0; i < args; ++i)
-				coords[i] = lua_tonumber(L, i + 1);
+				coords[i] = lua_tonumber(L, i + 2);
 		}
 
 		// make a closed loop