Erasure

ExchangeErasure::erase($member) erases a member's exchanges:

• their reservations are deleted;
• their open offers are withdrawn, which frees the items they held;
• erased:member takes their place in the offers and the transfers they had with other members, which stay those members' trades and points.

It returns an Erasure: the reservations deleted, the transfers and the offers changed. It erases from the stores it is given: an application without transfers or trades gives only the reservations. The points themselves — the spendings of the reservations, the transfers of the ledger — are erased by tilttek/points.