added comments
 removed LDAP_MAX_ATTR_LEN
 removed LDAP_COMPAT* from <ldap.h> but not code.
 move LDAP_DEFAULT_REFHOPCOUNT to ldap-int.h
 added experimental options macros
 added LDAP_CONTROL_REFERRALS macros
libldap:
 Replace ld_attrbuffer with per use allocated attributed.
 ldap_first/next_attribute attributes now must be freed (as per draft).
 unifdef -DLDAP_API_FEATURE_X_OPENLDAP_V2_REFERRALS

BerElement argument per latest IETF ldapext draft c api spec.
That is, caller is solely responsible for freeing the BerElement
allocated and returned by ldap_first_attribute.
Update man pages accordingly.
Update applications accordingly.