cad/openvsp: update to 3.17.0

From the ChangeLog:
(http://openvsp.org/blogs/announcements/2019/03/28/openvsp-3-17-0-released)

Features:

• CHARM Python export scripts
• Transparent screenshots
• Border toggle in menu
• Improved show axis toggle
• Export structure surfaces to IGES and STEP
• Design lift coefficient support for four-digit airfoils
• Propeller definition by thickness and CLi distribution
• Calculate integrated design lift coefficient for props
• BEM files in terms of thickness and CLi distribution
• Feather axis and offset control for propeller
• Implicit disk model for propeller
• STL solid names include tag number
• Tag unintersected triangles for STL export
• Increase tessellation limits
• Option to export props at origin (unintersected STL and STEP/IGES)
• Batch evaluation of Bezier surface points and normals (faster refresh)

Fixes:

• Restore visualization of CFDMesh sources and wake
• Don't crash when BOR XSec changed to Bezier
• Don't crash when reading Lednicer airfoils
• Import v2 multi-section wings properly
• Make key-corner default for rounded rectangle
• Reverse props with shifted construction line built correctly
• Don't allow insertion of XSec at negative index from API
• Don't allow comma as decimal point marker; fixes file corruption.
• Fix writing excressence drag label to XML file
• Fix unexpected ResetRemapID in files with conformal geometry