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/basic.cpp b/layers/basic.cpp
index 1e05475..ba56517 100644
--- a/layers/basic.cpp
+++ b/layers/basic.cpp
@@ -34,10 +34,10 @@
 
 static const VkLayerProperties globalLayerProps[] = {
     {
-        "Basic",
+        "basic",
         VK_API_VERSION,                 // specVersion
         VK_MAKE_VERSION(0, 1, 0),       // implementationVersion
-        "layer: Basic",
+        "layer: basic",
     }
 };
 
@@ -54,7 +54,7 @@
         "VK_LAYER_LUNARG_basic",
         VK_API_VERSION,
         VK_MAKE_VERSION(0, 1, 0),
-        "Sample layer: Basic, implements vkLayerExtension1",
+        "Sample layer: basic, implements vkLayerExtension1",
     }
 };