v2.0.0

New features

• Implement new algorithms in russell_lab such as B-spline, solution of cubic equations, and the solution of (dense) nonlinear systems
• Implement a new crate named russell_pde, including transfinite mapping, curvilinear coordinates (metrics), spectral collocation in 1D and 2D, and the finite differences method
• Implement a new crate named russell_nonlin for numerical continuation with natural and pseudo-arclength continuation for large sparse nonlinear systems of equations
• Improve the examples and documentation

Breaking changes

• In the russell_ode crate, the solve method of OdeSolver now takes an optional argument for configuring the output (e.g., dense output)