Change default navmesh agent radius to match nav agent node's default radius

doc/classes/NavigationMesh.xml

@@ -84,7 +84,7 @@
 		<member name="agent/max_slope" type="float" setter="set_agent_max_slope" getter="get_agent_max_slope" default="45.0">
 			The maximum slope that is considered walkable, in degrees.
 		</member>
-		<member name="agent/radius" type="float" setter="set_agent_radius" getter="get_agent_radius" default="0.6">
+		<member name="agent/radius" type="float" setter="set_agent_radius" getter="get_agent_radius" default="1.0">
 			The distance to erode/shrink the walkable area of the heightfield away from obstructions.
 			[b]Note:[/b] While baking, this value will be rounded up to the nearest multiple of [member cell/size].
 		</member>

scene/resources/navigation_mesh.h

@@ -85,7 +85,7 @@ protected:
 	float cell_size = 0.3f;
 	float cell_height = 0.2f;
 	float agent_height = 2.0f;
-	float agent_radius = 0.6f;
+	float agent_radius = 1.0f;
 	float agent_max_climb = 0.9f;
 	float agent_max_slope = 45.0f;
 	float region_min_size = 8.0f;