Update the chord parameter packing in  in main_wing_planform; added generic fuselage; added new wing geometry calculation classes to compute exposed and flapped wings

update naming to Wing.chords.root and Wing.chords.tip
Apply PEP8 formatting for wing planform files - not sure if these really conform to coding style.
Renamed chord_mid to chord_mid_trap to reflect trapezoidal wing. 
We can do that. The approach that I tried here was to be more "just in time" about it... and put in only the parameters that we need. We can discuss the pros and cons of the different approaches.