* Made it an error to specify address map and explicit ROM region.
* Made it an error if explicitly specified ROM region is not found.
* Made the ROM region tag apply relative to the current device.
-Cleaned up formatting for a couple more documentation pages.
The last(?) two changes are:
- Add a template parameter to everything (theoretically the address
space width, in practice a level derived from it to keep as much
compatibility between widths as possible) so that the shift size
becomes a constant.
- Change the syntax of declaring and initializing the caches and
specifics so that they're embedded in the owner device. Solves
lifetime issues and also removes one indirection (looking up the base
dispatch pointer through the cache/specific pointer).
