be applied by the backend.

Rename internal slapi_XXX API to slapi_x_XXX
Always set result code/matched/error text in operation parameter block
to make available to postoperation plugins

behaviour:

1. Plugins never return LDAP result codes, instead they return a
   small integer (0 or -1, others for special cases)
2. Preoperation plugins can abort processing by returning a non-
   zero value to the frontend
3. Postoperation plugins never abort processing (all are called)
   and their return values are ignored

plugins.

Use LDAP_SLISTs instead of per-struct list management for schema structs
misc cleanup and lint removal

Connection, Operation and Backend structures.

Ensure that SLAPI_MODIFY_MODS is set to an array of LDAPMods.

Implemented slapi_is_connection-ssl().