Formula specification release

• Autocart is now formula specification based: this better conforms to R modeling conventions
• Generic bug fixes

Resolved spatial weights

There were some noted issues with strange spatial weights matrices that were created from certain types of datasets, these should be resolved now.

Autocart initial stable release

Initial stable release of the Autocart package, an R package that contains code for modified regression tree splitting that explicitly incorporates spatial information in the splitting objective function while still leaving it out as an explicit predictor. Autocart is primarily intended for the modeling of a continuous response variable over a spatial field where spatial coordinate information is available for each training sample.