Disable NavigationMesh edge_max_length property by default

Disables NavigationMesh edge_max_length property by default.

doc/classes/NavigationMesh.xml

@@ -105,8 +105,8 @@
 		<member name="edge_max_error" type="float" setter="set_edge_max_error" getter="get_edge_max_error" default="1.3">
 			The maximum distance a simplified contour's border edges should deviate the original raw contour.
 		</member>
-		<member name="edge_max_length" type="float" setter="set_edge_max_length" getter="get_edge_max_length" default="12.0">
-			The maximum allowed length for contour edges along the border of the mesh.
+		<member name="edge_max_length" type="float" setter="set_edge_max_length" getter="get_edge_max_length" default="0.0">
+			The maximum allowed length for contour edges along the border of the mesh. A value of [code]0.0[/code] disables this feature.
 			[b]Note:[/b] While baking, this value will be rounded up to the nearest multiple of [member cell_size].
 		</member>
 		<member name="filter_baking_aabb" type="AABB" setter="set_filter_baking_aabb" getter="get_filter_baking_aabb" default="AABB(0, 0, 0, 0, 0, 0)">

scene/resources/navigation_mesh.h

@@ -99,7 +99,7 @@ protected:
 	float agent_max_slope = 45.0f;
 	float region_min_size = 2.0f;
 	float region_merge_size = 20.0f;
-	float edge_max_length = 12.0f;
+	float edge_max_length = 0.0f;
 	float edge_max_error = 1.3f;
 	float vertices_per_polygon = 6.0f;
 	float detail_sample_distance = 6.0f;