Refactor some functions so they can take arbitrary arguments

[jardinetsouffleton]

As of now, many functions need to be modified in order to run some experiments. For example:

• SeaPearl.featurize
• SeaPearl.global_featurize
• SeaPearl.update_features
• SeaPearl.feature_length
• SeaPearl.global_feature_length

Many of these functions rely on more information than is available in the currently accepted arguments. Therefore, in order to make SeaPearl more modular we will gain by refactoring them so they can accept more arguments.