Method writeArgumentConversion

tools/ffi.js:138–140

(file, i)

		file.write(`*arg${ i }`);
	}
	writeArgumentConversion(file, i) {
		file.line(`char** arg${ i } = XS->toStringHandle(the, mxArgv(${ i }));`);
	}
	writeResultConversion(file) {
		if (this.name.startsWith("const ")) {
			file.line("XS->fromStringX(the, mxResult, (txString)result);");