Directory restructuring of object.h

Break object.h into constituent files.
Reduce number of #includes in other GC header files.
Introduce -inl.h files to avoid mirror files #include-ing each other.
Check invariants of verifier RegTypes for all constructors.

Change-Id: Iecf1171c02910ac152d52947330ef456df4043bc
diff --git a/src/compiler/frontend.cc b/src/compiler/frontend.cc
index 31423ef..6ccbc07 100644
--- a/src/compiler/frontend.cc
+++ b/src/compiler/frontend.cc
@@ -19,7 +19,7 @@
 #include "dataflow.h"
 #include "ssa_transformation.h"
 #include "leb128.h"
-#include "object.h"
+#include "mirror/object.h"
 #include "runtime.h"
 #include "codegen/codegen_util.h"
 #include "codegen/mir_to_gbc.h"