RF: make fmri_dataset more general by allowing different reader functions for different file formats
RF+NF: fMRI datasets are loaded and written using more general code, allowing multiple file formats. experimental support for BV VMP
RF: remove map2nifti
RF: updated several files to reflect name change of map2nifti to map2fmri
RF: modularized fmri_dataset
NF: reading a dataset can also set attributes
NF: support for reading BV .glm
RF: cleanup for map2fmri
NF: support for storing datasets with LGLM headers (will convert this to VMP)