use ldap_find_control to find it. Added ldap_passwordpolicy_err2text().

and lots of cleanup (hence the commit)
(ldapmodify will need much more work for transactions)

Add ldap_find_control()

macros for transaction groupings

(back-sql needs to be updated)

Move ldapi into $(RUNDIR)/run/openldap

Works on BSD as well (equiv. to -DFD_SETSIZE=N).

Need to remove use of deprecated functions.