Add NavigationServer API to enable regions and links

Adds NavigationServer API to enable regions and links.

doc/classes/NavigationServer3D.xml

@@ -248,6 +248,13 @@
 				Create a new link between two positions on a map.
 			</description>
 		</method>
+		<method name="link_get_enabled" qualifiers="const">
+			<return type="bool" />
+			<param index="0" name="link" type="RID" />
+			<description>
+				Returns [code]true[/code] if the specified [param link] is enabled.
+			</description>
+		</method>
 		<method name="link_get_end_position" qualifiers="const">
 			<return type="Vector3" />
 			<param index="0" name="link" type="RID" />
@@ -312,6 +319,14 @@
 				Sets whether this [param link] can be travelled in both directions.
 			</description>
 		</method>
+		<method name="link_set_enabled">
+			<return type="void" />
+			<param index="0" name="link" type="RID" />
+			<param index="1" name="enabled" type="bool" />
+			<description>
+				If [param enabled] is [code]true[/code] the specified [param link] will contribute to its current navigation map.
+			</description>
+		</method>
 		<method name="link_set_end_position">
 			<return type="void" />
 			<param index="0" name="link" type="RID" />
@@ -734,6 +749,13 @@
 				Returns how many connections this [param region] has with other regions in the map.
 			</description>
 		</method>
+		<method name="region_get_enabled" qualifiers="const">
+			<return type="bool" />
+			<param index="0" name="region" type="RID" />
+			<description>
+				Returns [code]true[/code] if the specified [param region] is enabled.
+			</description>
+		</method>
 		<method name="region_get_enter_cost" qualifiers="const">
 			<return type="float" />
 			<param index="0" name="region" type="RID" />
@@ -786,6 +808,14 @@
 				[b]Note:[/b] If navigation meshes from different navigation regions overlap (which should be avoided in general) the result might not be what is expected.
 			</description>
 		</method>
+		<method name="region_set_enabled">
+			<return type="void" />
+			<param index="0" name="region" type="RID" />
+			<param index="1" name="enabled" type="bool" />
+			<description>
+				If [param enabled] is [code]true[/code] the specified [param region] will contribute to its current navigation map.
+			</description>
+		</method>
 		<method name="region_set_enter_cost">
 			<return type="void" />
 			<param index="0" name="region" type="RID" />