I forked sds.c from Redis given that it was very useful for the project for years, so I guess it may be useful in other contexts as well. There are a few change

I forked sds.c from Redis given that it was very useful for the project for years, so I guess it may be useful in other contexts as well. There are a few changes at API level compared to the Redis sds.c file, however most of the work went into documenting it.