adds partnerships resolves #170

[elmariachi111]

Partnerships are unique to a style A style can only have 1 partnership Partnerships can relate to >=1 partners A "partner" is actually the address of an origin collection Partnerships have an expiry date Partnerships have 1 beneficiary account The beneficiary gets 50% of platform shares when the partnership is active An exclusive partnership disallows minting splices on that style Exclusivity also applies to multi origins: if one origin is not included in the partnership, the mint is rejected. A non exclusive partnership allows minting on everything but pays out shares when not expired. When exclusive partnerships have expired, no shares are paid and minting is open to everybody To fully constrain a style to a certain collection(s), create a partnership for that collection and set the expiration date far into the future.

[elmariachi111]

Impact on minting fees

#main
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|  Splice                     ·  mint                    ·     186204  ·     241973  ·     203258  ·           47  ·     100.18  │
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#170
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|  Splice                     ·  mint                      ·     194331  ·     283482  ·     218860  ·           59  ·     122.17  │
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