Basis filter fix

[rachaelvp]

A few fixes related to filtering and interpretation.

• Extended functionality to support predictions on new data (i.e., not used in training) when reduce_basis is supplied in fit_hal.
• Moved copy_map filtering of x_basis after reduce_basis filtering of x_basis, and reduce_basis now filters basis_list as well.
• Added test for pairing the returned basis list with the coefficients. This pairing allows interpretation of the coefficients in terms of the cutoffs of the predictor values.

[nhejazi]

Merging since this seems resolved.