Added ground acceleration

Additionally added hysteretic angular nonlinearity based on moments

Moment-based nonlinearities available

Full Changelog: v0.2.0.6...v0.2.1.0

Fixed angular nonlinearities

Properly use angular deviations rather than just the base angle

Improved truss nonlinearity to include angles

Full Changelog: v0.2.0.4...v0.2.0.5

v0.2.0.4 - Random truss model improvements

This release

• adds Delauney triangulation random truss bar connections
• fixes partial lack of corotationality in random truss models
• fixes boundary condition prescriptions
• improves energy balance calculations to include nonlinear work

v0.2.0.3 - More sign fixes

Another sign fix

v0.2.02 - More bug fixes

v0.2.0.2

More bug fixes

v0.2.0.1 - Truss bug fixes

Fixed mishandling of boundary conditions for the random truss systems

Also added a new function to the systems to be able to validate the simulation with an energy balance

v0.2.0 - Added corotational system

Now a totally arbitrary corotational system can be created, including nonlinearities.

Syntactically similar to all other MDOF system prescriptions, allowing full arbitrary solutions.

Bug fixes for corotational grid system

v0.1.10.5

bug fixes for corotational grid