Lower Taker Fees to 2.00% & Eliminate Taker Fee Discounts

Summary:

1. Lower fees paid on winnings by takers to 2.00% from 4.00%
2. Eliminate taker fee discounts

As requested, this proposal will lower taker fees from 4.00% to 2.00%, while also eliminating fee discounts for takers. Both changes are being batched as it doesn't make sense to do just one or the other. Lowering the headline taker fee will make SX far more competitive for both existing users and newcomers alike, and brings SX in-line with other betting exchanges like Smarkets, etc. Removing the fee discounts (for takers only) cushions the blow in terms of fee capture for the protocol.

See discord for discussion