layers: Rename Layer/library/json files for consistency

Renamed layers from (for example) xxx_DrawState to xxx_draw_state
Renamed JSON files
Renamed libraries
Renamed object_track.* to object_tracker.*
Renamed apidump.h to api_dump.h
Renamed screen_shot layer to screenshot
Renamed APIDump layer settings file options to ApiDump
Bug fixes here and there from prior renames
diff --git a/vk-generate.py b/vk-generate.py
index 36a830d..0a98602 100755
--- a/vk-generate.py
+++ b/vk-generate.py
@@ -259,7 +259,7 @@
                     "vkEnumerateInstanceLayerProperties",
                     "vkEnumerateInstanceExtensionProperties"
                 ],
-                "layerMulti": [
+                "layer_multi": [
                     "multi2GetInstanceProcAddr",
                     "multi1GetDeviceProcAddr"
                 ]
@@ -271,8 +271,8 @@
             return
 
         self.library = self.argv[0]
-        if self.library == "VKLayerMulti":
-            self.exports = library_exports["layerMulti"]
+        if self.library == "VkLayer_multi":
+            self.exports = library_exports["layer_multi"]
         else:
             self.exports = library_exports[self.argv[1]]
 
@@ -317,7 +317,7 @@
         body.append("EXPORTS")
 
         for proto in self.exports:
-            if self.library != "VKLayerSwapchain" or proto != "vkEnumerateInstanceExtensionProperties" and proto != "vkEnumerateInstanceLayerProperties":
+            if self.library != "VkLayerSwapchain" or proto != "vkEnumerateInstanceExtensionProperties" and proto != "vkEnumerateInstanceLayerProperties":
                 body.append( proto)
 
         return "\n".join(body)