...used for now to transport @deprecated information.

Also, improve Idx-String (formerly Idx-Name, but also used for UTF-8 annotations
now) format, using the 0x80000000 for the indirection rather than the base case.
(And the README erroneously used "Offset of" Idx-String all over the place.)

Change-Id: I7003b1558ab536a11a9af308f9b16a7ef8840792