New inference 🎨

[jcblemai]

Functionalities to support several inference algorithms, make flepimop install a one-line thing, overhaul file saving and analysis

• convert the internal representation of epi states from data frame to xarray
• save epi state only on command
• update documentation for new packages
• implements class for statistics
• implement likelihood computation
• Finish and test statistic class FOR ROUND
• Make so we can resume FOR ROUND while not fitting all parameters but some of them (the other ? drawn ??)
• make the folder draw thing
• workflow config
• make an inference benchmark
• so many things...
• implement emcee as a script
• rewrite resume and continuation batch
• rewrite current inference algorithm
• make it possible to batch with and without MPI, or on single node.

I made a mistake and did here the changes to remove time and to switch the R code to date, sorry about that. The changed R files are because of this.

[jcblemai]

• The new inference works but there is no workflow like resume yet.
• but important to merge it know because the old inference is fixed in this branch

The merge-base changed after approval.