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/layers/generic.h b/layers/generic.h
index 955ea7d..bc5c555 100644
--- a/layers/generic.h
+++ b/layers/generic.h
@@ -31,7 +31,7 @@
 #include "vulkan/vk_layer.h"
 
 /*
- * This file contains static functions for the generated layer Generic
+ * This file contains static functions for the generated layer generic
  */
 
 // The following is for logging error messages:
@@ -50,7 +50,7 @@
         "VK_LAYER_LUNARG_generic",
         VK_API_VERSION,                 // specVersion
         VK_MAKE_VERSION(0, 1, 0),       // implementationVersion
-        "layer: Generic",
+        "layer: generic",
     }
 };
 
@@ -59,7 +59,7 @@
         "VK_LAYER_LUNARG_generic",
         VK_API_VERSION,                 // specVersion
         VK_MAKE_VERSION(0, 1, 0),       // implementationVersion
-        "layer: Generic",
+        "layer: generic",
     }
 };