Version number, name, and build details.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

version.c

@@ -0,0 +1,11 @@
+#include "version.h"
+#include "gen_version.h"
+#include <stdio.h>
+
+char *version_and_exit(const void *unused)
+{
+	printf("%s\n"
+	       "aka. %s\n"
+	       "Built with: %s\n", VERSION, VERSION_NAME, BUILD_FEATURES);
+	exit(0);
+}