Update the CIL documentation for the in-statement processing and
duplicate macro and block declarations with block inheritance.
Duplicate macro and block declarations are allowed if they occur as
the result of block inheritance. Document the fact that inherited
macros are overridden by any macros already declared in a
namespace and that declaring a block in a namespace that will
inherit a block with the same name can be used to allow in-statements
to be used on the block.
The new in-statement syntax still supports the old syntax but adds
the ability to specify whether the in-statement should be resolved
before or after block inheritance is resolved.
Signed-off-by: James Carter <jwcart2@gmail.com>