Shove kicad2step into pcbnew itself with a new cli

thirdparty/argparse/samples/custom_assignment_characters.cpp

@@ -0,0 +1,27 @@
+#include <argparse/argparse.hpp>
+#include <cassert>
+
+int main(int argc, char *argv[]) {
+  argparse::ArgumentParser program("test");
+  program.set_prefix_chars("-+/");
+  program.set_assign_chars("=:");
+
+  program.add_argument("--foo");
+  program.add_argument("/B");
+
+  try {
+    program.parse_args(argc, argv);
+  } catch (const std::runtime_error &err) {
+    std::cerr << err.what() << std::endl;
+    std::cerr << program;
+    std::exit(1);
+  }
+
+  if (program.is_used("--foo")) {
+    std::cout << "--foo : " << program.get("--foo") << "\n";
+  }
+
+  if (program.is_used("/B")) {
+    std::cout << "/B    : " << program.get("/B") << "\n";
+  }
+}