Added a dict wrapper that acts like an object

[dsblank]

@Nick-Hall had an interesting idea to make the raw dict from JSON act like an object. In that way, instead of writing:

if data["gender"] == Person.MALE:

you could write:

if data.gender == Person.MALE:

And if you rename data to person it looks like regular gramps for all of the attributes of all of the Gramps objects:

if person.gender == Person.MALE:

This has all of the benefits of quick access (no object creation) with a convenient syntax.

However that could create some confusion because methods can't be called as it isn't a real Person. With a couple of additional lines, it can act as a real object:

if person.get_gender() == Person.MALE:

This allows us to use the full object attribute and methods, only creating an object when necessary. Sometimes it is necessary, such as:

person.person_ref_list[0].get_referenced_handles()

(Although this only instantiates a PersonRef(), much cheaper than instantiating the whole Person)

With this PR applied, I found that person.get_gender() was 4.4 times slower than person.gender. The only downside with this PR is that those writing code (filter rules, for example) might not realize that they are creating an object when it is not necessary.

[dsblank]

@stevenyoungs no data leakage! :)

[dsblank]

@Nick-Hall, some more decisions to make:

1. Do we want to allow attribute syntax (data.gender) instead of dictionary syntax (data["gender"])? I think it is a nice enhancement, and is a very minimal change and cost.
2. Do we want to allow method-calling (data.get_gender())? Although it hides object creation, it eliminates confusion, is sometimes needed, and is easy to implement.
3. Shall we go with this implementation? I can't think of a better method to accomplish the above.

Let me know what you think, and I'll go with the decision on the next set of changes.

[Nick-Hall]

@dsblank I'm happy with all of this. The attribute syntax is neat and concise, method-calling could be useful, and I don't have any objections to your implementation.

I was waiting for other comments before adding my opinion.

[dsblank]

I'll work on adding tests, and prepare for moving from draft status.

[dsblank]

Tests added, ready for review.