Add makeDefaultValue + fix duplicate protos

The memoize decoration function now provides access to the internal cache.

Change JS build target to 2017.

Update all dependencies + add HList.find

Enable insertion of other filters and filter builders into an existing filter builder.

Also provide more debugging utility methods.

An HRef object can now be created using an HStr.

Fix parsing empty inner grid.

Added support for non standard compulsory application level tags.

Check the kind of each tag found in a namespace for a dict.