Documentation for Periodic Capability

[jbschroder]

We need to add a discussion about the periodic capability to the user manual. Don't forget to

• Turn it on with SetPeriodic
• Issues with num time points being divisible by cfactors.
• FRefine will even add points for you, so that this is true
• Discuss that the coarsest grid is solved with FCF-relaxation, and you set the number of sweeps by setting nrelax on the last possible level (i.e., max_levels-1). This is true, even if you never generate max_levels levels.
• Use a nice picture like this one to explain things braid-periodic.pdf