Added support for optional explanation parameter to the \versionadded macro. Refactored do_cmd_versionadded() and do_cmd_versionchanged() to do most of the work in a helper function, with the do_cmd_*() wrappers just supplying a portion of the replacement text.

/* strdup() replacement (from stdwin, if you must know) */

#include "pgenheaders.h"

char *
strdup(const char *str)
{
	if (str != NULL) {
		register char *copy = malloc(strlen(str) + 1);
		if (copy != NULL)
			return strcpy(copy, str);
	}
	return NULL;
}