converted smbd to use NTSTATUS by default

converted smbd to use NTSTATUS by default
major changes include:

- added NSTATUS type
- added automatic mapping between dos and nt error codes
- changed all ERROR() calls to ERROR_DOS() and many to ERROR_NT()
  these calls auto-translate to the client error code system
- got rid of the cached error code and the writebmpx code

We eventually will need to also:
- get rid of BOOL, so we don't lose error info
- replace all ERROR_DOS() calls with ERROR_NT() calls

but that is too much for one night