The prohibition against mixed fabrics was a ceremonial law, pertaining to the commonwealth of Israel which passed away with the Oblation of Christ, the fulfillment of all ceremonial types.
Unfortunately Jesus doesn't say that. All the laws are in effect until heaven and earth have passed away and you won't make it into heaven without being even more righteous than the pharisees (and they obtained their righteousness through following the complete law).
That's the moral law he is referring to. The Ten Commandments and their moral inferences. The Westminster Confession says,
III. Besides this law, commonly called moral, God was pleased to give to the people of Israel, as a church under age, ceremonial laws, containing several typical ordinances, partly of worship, prefiguring Christ, His graces, actions, sufferings, and benefits; and partly, holding forth divers instructions of moral duties. All which ceremonial laws are now abrogated, under the New Testament.
4] (HEB 9) HEB 10:1 For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect. GAL 4:1 Now I say, That the heir, as long as he is a child, differeth nothing from a servant, though he be lord of all; 2 But is under tutors and governors until the time appointed of the father. 3 Even so we, when we were children, were in bondage under the elements of the world. COL 2:17 Which are a shadow of things to come; but the body is of Christ.
 1CO 5:7 Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us. 2CO 6:17 Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you, JUD 23 And others save with fear, pulling them out of the fire; hating even the garment spotted by the flesh.
 COL 2:14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross. 16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days: 17 Which are a shadow of things to come; but the body is of Christ. DAN 9:27 And he shall confirm the covenant with many for one week: and in the midst of the week he shall cause the sacrifice and the oblation to cease, and for the overspreading of abominations he shall make it desolate, even until the consummation, and that determined shall be poured upon the desolate. EPH 2:15 Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace; 16 And that he might reconcile both unto God in one body by the cross, having slain the enmity thereby.http://www.reformed.org/documents/wcf_with_proofs/
Mark 7:19 Jesus says, "Do you not understand that whatever goes into the man from outside cannot defile him, 19 because it does not go into his heart, but into his stomach, and [g]is eliminated?” (Thus He declared all foods clean.) "
That's an abrogation of ceremonial law: the dietary law.
I'd be interested in what you'd classify as good slave trade.
First, the term "trade" may be applicable to some aspects of it but not many. Temporary Retributive (criminal) that all societies have our present society included or for debt (voluntary). Nothing generational or hereditary.