fb-code-cleanup-3

I consolidated some more code and added a switch to turn the validation set on and off.

- Created boolean 'use.validation' which automatically allows for use of a validation set, or not.

- When 'use.validation' is TRUE, data is split accordingly: 45% training, 30% validation, & 25% testing. When it is false: 75% training, & 25% testing.

- Fixed a bug where ANN in-sample accuracy was being incorrectly reported.

- All models' in-sample accuracy is now dynamically calculated, and requires less code.

- The formula used for training has now been pulled out into its own variable, so it can now be set once, and applied to all models.