Enhance ZPublisher "type suffixes" and "ZTUtils" ...

[d-maurer]

... by functionality from dm.zopepatches.ztutils?

ZTUtils.make_query (and friends) allow together with ZPublisher's type suffixes to pass typed information between requests. However, there are some weaknesses.

dm.zopepatches.ztutils addresses the following weaknesses:

• missing support for None
• missing support for empty lists/tuples
• limited support for nested structures
• fixed set of supported types

by

• allow for the registration of extensions (essentailly new type suffixes and corresponding converters); used to handle None and deeply nested JSON serializable structures (via a json extension)
• use :tokens:default to provide a default for empty list/tuple

[dataflake]

You're welcome to create a PR that integrates functionality directly, meaning without introducing dependencies to outside packages.