WIP: Covid sde (#867)

* First stab at the ODEs

* System of ODEs for the  simple case

* Converted to the b, specification

* Converted to R instead of beta

* Added material on the SDE

* Added simple example as well as sketch on stochastics.

* Up to stochastics...

* Done with the SDE.  About to do the Jumps

* Finished the Jump Diffusion

* JuMP Diffusion compiling and running

* A few more visualization ideas

* minor corrections

* Moved to continous_time section

* COVID SDE lecture edits (#870)

* Comment on heuristics in the CIS process

* Plotting tweaks with labels, etc.

* minor typos and rephrasing

* Reorganization of the SDE stuff in progress

* Updated the SDE model up to the output_func

* Added reinfection and fixed a few typos

* Updated sde and detemrinistic lectures

Co-authored-by: John Stachurski <john.stachurski@gmail.com>
Co-authored-by: Christopher Rackauckas <accounts@chrisrackauckas.com>

conf.py

@@ -463,7 +463,8 @@
     'more_julia': [],
     'multi_agent_models': [],
     'time_series_models': [],
-    'tools_and_techniques': []
+    'tools_and_techniques': [],
+    'continuous_time': []    
 }
 
 jupyter_download_nb_execute=True