Add a python script to read dclunie's tpl files.
Support for private dictionaries.

The makedict.py script has been modified so that it can generate
hash tables for private dictionaries, and various classes have been
modified to support private dictionaries.
Use a hash table to store the private dictionaries.

Rather than store the private dictionaries in an array, store them
in a hash table in order to accelerate the lookup.
Add "Private Creator" output to dicomdump.

This just causes "Private Creator" to be used as the name of all
private creator elements that are encountered.
Add a utility to parse .tpl files for makedict.py