The SEXPR class is a useful general-purpose S-Expression library
class and can (maybe) be used else where. It also should get
test coverage, as even if noone else uses it, it's critical for the
kicad2step exporter.
Also add some test coverage for some kicad2step routines. For now,
they're not useful outside kicad2step, but they are at least a useful
reference for S-Expression parsing.
The file filter wild card was defined incorrectly causing the file picker
to not display *.stp and *.step file extensions. Change the wildcard per
wxFileDialog documentation.
Prevent the file extension from being forced to .stp even when the user
defined a different extension in the file picker.
Override TransferDataFromWindow to test for file existence and warn user
only once if a file overwrite can occur.
Minor STEP export dialog string and layout improvements.
Make kicad2step honor user's file extension rather than always setting it
to .stp.
Fixes lp:1709636
https://bugs.launchpad.net/kicad/+bug/1709636
John Beard
Maciej Suminski
Wayne Stambaugh
jean-pierre charras
Simon Wells
Cirilo Bernardo