Engine api

[granawkins]

This is the last of 3 big PRs. It consists of two commits:

1. Update Tests

Implement a few small changes which require updating the test results. These were discussed in the last dev call.

2. New Class implementations

• A NumpyEngine and TensorflowEngine which perform the most expensive calculations on the cpu or gpu, respectively
• A new scoring attribute for Base_GP which determines how fitness is calculated and what other fields are calculated
• 3 new GP classes: Regressor_GP, MultiClassifier_GP and Matchin_GP which implement scoring for the three Karoo 'kernels'
• Several small tweaks and improvements

This is the last of the major updates I wanted to make asap. Things which I've skipped but should still be addressed:

• The interactive mode should be tested and debugged
• The pause menu could be streamlined
• The save/load systems should be optimized

[kstaats]

In a prior email thread, the "Matchin_GP" ("Matching_GP"?) was going to be rebuilt to apply regression instead, as the original "match" function is not truly evolutionary, rather a sophisticated guess. If so, perhaps this should be renamed to "Custom_GP" or "User_GP"?