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/jdwp/jdwp.h b/src/jdwp/jdwp.h
index 6cac0f6..71bae08 100644
--- a/src/jdwp/jdwp.h
+++ b/src/jdwp/jdwp.h
@@ -30,8 +30,9 @@
 struct iovec;
 
 namespace art {
-
+namespace mirror {
 class AbstractMethod;
+}  // namespace mirror
 class Thread;
 
 namespace JDWP {