#46 Functions for passing MDB types as opaque pointers

[Jonathan Monroe]

In order to use mdblib as a dynamically loaded library,
there must be a set of functions for accessing the
application-level data in the MDB data structures.
Instances of the structures can then be retained and
passed to the lib as opaque pointers. The application
doesn't have to know anything about the data types
themselves.

I have taken a first cut at supplying missing functions
for accessing some frequently used fields.

The attached diff file is based on CVS source on
2005-12-30.

[Jonathan Monroe]

Diff file for adding access functions to libmdb source files.