r435: a major upgrade for ldb

r435: a major upgrade for ldb

 - added the ability to mark record attributes as being CASE_INSENSITIVE, WILDCARD or INTEGER.

 - added the ability to support objectclass subclasses, and to search by a parent class

 - added internal support for case insensitive versus case sensitive
   indexing (not UTF8 compliant yet)

 - cleaned up a number of const warnings

 - added a number of helper functions for fetching integers, strings and doubles

 - added a in-memory cache for important database properties, supported by a
   database sequence number

 - changed some variable names to avoid conflicts with C++
(This used to be commit f2bf06f25c2e6c744817711c7bedbd1d3b52f994)