Enable time interpolation for time dependent input from files
Add ability to provide time dependent input from a sequence of files. This is now possible for the Floquet stability analysis but should be extended and generalised to other applications / solvers.
Periodic time interpolation using Fourier interpolation for periodic problems, aside from Floquet I think this could be used to find eigenmodes of time dependent advection-diffusion problems, but possibly also others.
Segment-like time interpolation (non-periodic) could be useful for the Nonlinear Transient Growth. The isiest is probably linear interpolation.