Decouple Thrown Object from Examples

[teubert]

Problem: Some examples cannot be run alone as scripts because they're dependent on other examples. Since it's setup as a package imports have to be from .[file_name] import [thing] in order to support python -m examples.[file_name]. However, this breaks when you run a file by itself from within examples directory (e.g., press run in IDE). For that to work the command from [file_name] import [thing] is needed (without the period). Multiple users have had issues with this

Solution: remove the intra-package dependency by adding thrown_object to prog_models.models. Set it up to not be imported by default (not part of init.all), and update the examples to use this version instead of the version defined in examples.new_model

Closes #137

[kjjarvis]

This change looks great - good adjustment to allow easy implementation for many users