RF: first pass at a gaussian pRF model and fit procedure
RF: removed the Stimulus class features from config
RF: beautified the execution script
RF: added popeye.stimulus to the imports
RF: removed all features that are now redundant with popeye.prf
RF: moved Stimulus specific features from popeye.utilities
RF: added test for popeye.prf and popeye.stimulus and removed redundancy from previously used tests