Clarified a documentation statement about circular references.

Change-Id: I8f3c50085f89037995ab9f26b28d3c83667e9d6f
Fixed "unused private field" warning for clang.

Bug: 17095037
Change-Id: Iedbe56f6ddc0ba7876896b0bb7ed9da8e6a85f7e
Tested: on Linux & OS X.
Schemas now support include files.

Bug: 15521443
Change-Id: I2e1ef97e7225a1a0ecf2ca65e31d49d443003747
Tested: on Linux.
Referring to types from other namespaces in C++ now works correctly.

Previously, it would ignore the fact that the type comes from a
different namespace. Now they are pre-declared in their own namespace,
and referenced with a qualified name if necessary.

Bug: 16851682
Change-Id: I5cb625b86d28e7436b9e93c70a0fa16a600d9884
Tested: on Linux