parametric glider

parametric glider, work in progress
+ change profiles for elevator and rudder
+ improve elevator mount
inspired by https://www.thingiverse.com/thing:12634 but rewritten from scratch
the approach for the approximation of the wing profiles uses and thus has less "ripple" when zooming in.
Inititally triggered by my curiosity how one would generate CNC-data for foam core milling.

glider-ZoneV2.scad contains a main wing build from an STL-file-export of an xflr5 design file published by [Gerald Taylor](https://www.rcgroups.com/forums/showthread.php?1568108-Zone-V2-moldie-reference-design) on rcgroups.
Just found out to export STL from xflr5 and to set the number of panels.