Model Vis inline with Callback ipynb

[Xyzic]

Updated modelvis to be streamlined and a bunch of other files for testing/examples.

Updated gitignore to disregard wip stuff and already existing examples

[Xyzic]

Added in new notebook, modified a few core files as requested

[matthewturk]

I have a couple changes, but one that is pretty important -- socket_type should not be connection. I don't completely know why, but that seems to be a reserved word that breaks things and prevents clicking and creating new connections. Change it to bytes. But longer term, we actually need to parse this from the yggdrasil model.

[matthewturk]

A couple additional things:

• Format the code with black
• I don't think we should be returning any instances. The model_loader function should merely transform the input yaml into a set of dict objects that can be supplied to add_component. This helps to make sure that the SocketCollection instance that's used by all the different components is the same.
• We need to parse the data types being accepted and emitted by the different slots. That means using the default that yggdrasil assumes, if we need to; this is one (of several) instances that relying on yggdrasil's normalization code would be helpful. (@langmm may have thoughts on how to have it fill out the defaults without instantiating any compilation or execution procedures.)
• I believe you can considerably simplify the dictionary translation code.

[Xyzic]

Everything done except the third bullet and probably more can be done for the fourth.

[Xyzic]

Quick comment on the socket types -- this should always be bytes as Yggdrasil always returns bytes, so there shouldn't need to be a need to parse out the actual type. The code does that in a list just in case, but in all test cases so far it has been bytes