Set flag for hasSubordinates and subschemaSubentry. Strip dynamic attributes
before storing entries in syncrepl.

frontend stuff moved into a database structure, essentially to allow overlays to be processed before database selection; passes all tests (ITS#3080)

slightly rework user/operational attributes handling (including fixing a bug in the logic of the previous change to backend_operational()); cleanup; more improvements to slapo-rwm and back-relay

revert previous change; anticipate backend_operational before overlays callbacks (thanks, Howard); rework overlays cycle to allow callbacks to free themselves (thanks Howard)

the lastmod command will fail.  To be set by backends
(e.g., back-ldap) which force the value of SLAP_DBFLAG_NOLASTMOD
database flag.

initial/final string settings from any string settings.

honor sizelimit requests on the overall count when pagedResults control is used; cleanup and more features

improve previous commit; now special limit on the number of total entries of a paged results can be set via the limits.  Need to decide whether the default should be unlimited or what