Fixed HC49 crystal SMD variants
This PR doesn't change the form of the existing packages, it simply updates the data structure according to https://github.com/KiCad/kicad-packages3D/pull/539#issuecomment-481833107 Please review and suggest amendments if necessary before merging. The updated FreeCAD source file is here: https://github.com/KiCad/kicad-packages3D-source/pull/218