r24667: Finally merge the registry improvements that Wilco Baan Hofman and I have

r24667: Finally merge the registry improvements that Wilco Baan Hofman and I have
been working on for at least half a year now. Contains the following
improvements:

 * proper layering (finally!) for the registry library. Distinction is
   now made between 'real' backends (local, remote, wine, etc) and
   the low-level hive backends (regf, creg, ldb, ...) that are only used
   by the local registry backend
 * tests for all important hive and registry operations
 * re-enable RPC-WINREG tests (still needs more work though, as
							   some return values aren't checked yet)
 * write support for REGF files
 * dir backend now supports setting/reading values, creating keys
 * support for storing security descriptors
 * remove CREG backend as it was incomplete, didn't match the data model
   and wasn't used at all anyway
 * support for parsing ADM files as used by the policy editor (see lib/policy)
 * support for parsing PREG files (format used by .POL files)
 * new streaming interface for registry diffs (improves speed and memory usage
	for regdiff/regpatch significantly)

   ... and fixes a large number of bugs in the registry code