Mssfp

- Added support for array of alphas for ssfp simulation
- Added support to generate phantoms from a list of tissue parameters

Added

Added
- Updates to phantom generators
- Updated slice selection in load_dataslice
- Added print_dataset_info, get_dataset_info
- Added noise option off-resonance field map simulation
- Cleaned up and refactored phantom code
- phantom.generate_ssfp_dataset() can be used to generate a 3d ssfp dataset from a various phantom types

Added
- Initial release with core SSFP simulation and reconstruction capabilities
- Phantom generators including Shepp-Logan, block phantoms, and brain phantoms
- Multiple banding artifact removal reconstructions:
- Sum of squares
- Elliptical signal model
- Super field of view (superFOV)
- PLANET implementation for T2/T1 mapping
- Jupyter notebook examples demonstrating various features
- Basic SSFP simulations
- Support for Python 3.8+