Strip theory

[atagg2]

Addition of strip theory to calculate viscous drag

[andrewning]

• the example won’t work as is. you have an input parameter res that is not provided (the list of Reynolds number corresponding to the provided data).
• You should also generate the figure in the docs on the fly so you can ensure that the code you provide is actually running what you expect (in this case it'll throw an error and we'd want to catch that). I'd need you to provide the data in this case since it's not here in the code for the figure to be re-generated.
• strip_theory_drag! is hard coded to the first surface.
• this assumes that the same airfoil ls used throughout the surface, and on every surface. would need to specify those per section like twist or other airfoil variables. @atagg2 @rymanderson