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/swapchain.cpp b/layers/swapchain.cpp
index 255fb1d..a60ed20 100644
--- a/layers/swapchain.cpp
+++ b/layers/swapchain.cpp
@@ -58,10 +58,10 @@
 
 static const VkLayerProperties swapchain_global_layers[] = {
     {
-        "Swapchain",
+        "swapchain",
         VK_API_VERSION,
         VK_MAKE_VERSION(0, 1, 0),
-        "Validation layer: Swapchain",
+        "Validation layer: swapchain",
     }
 };