Add a simple commandline parser example.

Also cleaned up a few files.  Since these were pulled from various
scratch repos from informal ISO discussions over the years, they don't
quite line up.  This at least gets everything building again.

example.cc

@@ -0,0 +1,35 @@
+static_assert( __cplusplus > 2020'00 );
+
+#include "ProgramOptions.h"
+
+namespace
+{
+	using namespace Alepha::literals::option_literals;
+	using namespace std::literals::string_literals;
+
+	int optionA= 42;
+	std::optional< std::string > optionB;
+
+	auto init= Alepha::enroll <=[]
+	{
+		--"set-a"_option << optionA << "The option is an integer.  !default!";
+		--"set-b"_option << optionB << "The option is a string, no defaults.";
+	};
+}
+
+int
+main( const int argcnt, const char *const *const argvec )
+try
+{
+	const auto args= Alepha::handleOptions( argcnt, argvec );
+
+	std::cout << "A is set to: " << optionA << std::endl;
+	std::cout << "B is set to: " << ( optionB.has_value() ? optionB.value() : "nullopt"s ) << std::endl;
+
+	return EXIT_SUCCESS;
+}
+catch( const std::exception &ex )
+{
+	std::cerr << "Error: " << ex.what() << std::endl;
+	return EXIT_FAILURE;
+}