loader: Update the loader to 1.0.39

Add new extensions for 1.0.39.  Also, updated layers to include
minimal set of functionality for 1.0.39 extensions. Extensions include:
 - VK_KHR_get_physical_device_properties2
 - VK_KHR_shader_draw_parameters
 - VK_EXT_direct_mode_display
 - VK_EXT_display_surface_counter
 - VK_EXT_display_control

Also, redo the LoaderAndLayerIf document.

Change-Id: I10412086da7a798afe832a3892e18f606259b5af
diff --git a/scripts/threading_generator.py b/scripts/threading_generator.py
index 8dfdb7e..05e659f 100644
--- a/scripts/threading_generator.py
+++ b/scripts/threading_generator.py
@@ -400,9 +400,12 @@
             self.appendSection('command', decls[0])
             self.intercepts += [ '    {"%s", reinterpret_cast<PFN_vkVoidFunction>(%s)},' % (name,name[2:]) ]
             return
-        if "KHR" in name:
+        if ("KHR" in name) or ("KHX" in name):
             self.appendSection('command', '// TODO - not wrapping KHR function ' + name)
             return
+        if ("NN" in name):
+            self.appendSection('command', '// TODO - not wrapping NN function ' + name)
+            return
         if ("DebugMarker" in name) and ("EXT" in name):
             self.appendSection('command', '// TODO - not wrapping EXT function ' + name)
             return