Hello,
Some parts of that feature are still available in the core but there is no more buttons in the carts/wishlists for the conversion.
Due to possible unwanted side effects and that carts and wishlist do not have same kind of restrictions ; a cart/wishlist conversion can result to an error (which would empty the cart/wishlist).
I would rather recommend you to use the "move to..." feature.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.