Note: this breaks LDAP_COMP_MATCH and SLAP_ZONE_MALLOC. But they
were probably broken already anyway.

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

Converted ch_malloc, ch_calloc and ch_realloc calls to SLAP_MALLOC and
SLAP_CALLOC in add_value/add_value_one functions and propagated errors to
all functions that use these functions.

add {create,modify}Timestamp to subschema subentry (SHOULD per RFC2251; use server startup time to be conservative)

inaccessible, this is original code, not contributed.)

Not sure how best to populate matchingRuleUses...