v0.22.1

Multiple bug-fixes and new features:

• Breaking Change: Changed how time integration responses are requested. Can now request displacement, velocity, and acceleration derivatives simultaneously through a dictionary syntax.
• Breaking Change: Removed time integration from ShapeArray object. Correct approach is to compute a System object from the ShapeArray and then time integrate.
• Added MAC and MAC plots directly to ShapeArray objects
• Added shaker substructuring capabilities.
• Allowed System objects to have massless degrees of freedom.
• Added an example problem in the documentation dealing with shaker modeling and simulation.
• Fixed some image issues in the documentation.
• Fixed some issues and added features when reading Rattlesnake data.
• Added ability to save Geometry objects to .mat files.
• Build and ESCDF visualizer user interface, allowing users to explore an ESCDF file and visualize the data inside of it.
• Added ability to compute a transformation matrix to transform between geometries containing differing coordinate systems.
• Added matrix multiplication functions allowing Matrix objects to be multiplied by data.
• Added ability to export Pole Lists from PolyPy, allowing additional curve-fitting to be performed offline, or to fit shapes using a different dataset than the poles were fit to.
• Added some options to not save abscissa data to disk to reduce file sizes.
• Efficiency improvements when making a modal system from mode shapes containing large numbers of degrees of freedom.
• Added ability to multiply System objects by a scalar to scale the system matrices.
• Added some updates to ESCDF geometry readers to accept point clouds without coordinate systems, tracelines, or elements defined.
• Fixed a bug where mass was not applied to the rigid body mode shapes when computing rigid body modes from geometry and mass properties.