r8082: large rewite of ldb_dn.c

r8082: large rewite of ldb_dn.c

- we do not support multpiple attribute components anymore, makes code a lot easier
  they will be readded later if we found out they are really used, so far my tests
  show w2k3 do not handle them as well

- fix escaping issues, move component value to be in an ldb_val structure
  still need to handle binary values case

- make cononicalize functions leak less memory by giving a specific memory context

- fix tests scripts so that test-ldap can start
- make test not delete databases on completion so that I can inspect them
(This used to be commit 624a73148d125690ce18515f19231d26df207738)