The reason we need this is to make multi-tdb transactions safe, with
the partition module. The linked_attributes and repl_meta_data modules
now do extra processing when the transaction ends, and that processing
can fail. When it fails we need to cancel the transaction, which we
can only do if the hook is on the prepare commit instead of the end
transaction call. Otherwise the partition module cannot ensure that no
commit has been done on another partition.

I always found it hard to remember some of the options. We might as
well use popt to give us the full list

This allows the ldb tools to show their full command line options

Two controls with the same OID makes no sense, as they may
have different data attached

This function provides a easy function for displaying a ldb_message
structure in a human readable format. It is especially useful for
calling in gdb.

- remove trailing spaces and tabs
- shorten some variable names for readability
- try to break superlong lines for readability

Michael