Report diagnostics from libconfig when parsing fails.

src/parse.c

@@ -403,6 +403,8 @@ libmegapixels_load_file(libmegapixels_devconfig *config, const char *file)
 	config_init(&cfg);
 	if (!config_read_file(&cfg, file)) {
 		fprintf(stderr, "Could not read %s\n", file);
+		fprintf(stderr, "%s:%d - %s\n",
+			config_error_file(&cfg), config_error_line(&cfg), config_error_text(&cfg));
 		config_destroy(&cfg);
 		return 0;
 	}
@@ -571,4 +573,4 @@ libmegapixels_init(libmegapixels_devconfig **config)
 	*config = calloc(1, sizeof(libmegapixels_devconfig));
 	init_log(0);
 	return 1;
-}
+}