Implement SPORF in Proglearn: predict function, documentation

[parthgvora]

The end goal is to create an sklearn compliant SPORF in proglearn that is modular enough to add different kinds of oblique trees in the future (i.e. MORF). This issue is in tandem with #351

1. Implement the predict & predict_proba functions for the oblique tree
2. Write unit tests for above functions.
3. Write sklearn compliant documentation for new class
4. Feature request for sklearn oblique trees: write "Describe your workflow section"

[parthgvora]

Please assign @jmandavilli this issue

[jmandavilli]

Could I be assigned to this issue

[levinwil]

Closing, per PR #374

[PSSF23]

Reopen until performance and correctness verified with paper figures