[RIP-4] Staking Mechanism

This assumes that RIP-1 and RIP-3 (or their derivatives) have been approved

Summary: Introduces a new staking mechanism that will reward long term retention in the protocol.

Background: Staking has proven to be a very strong retention tactic for various DeFi protocols (look at Yearn, Harvest and many others).

Abstract: The staking model will enable people who stake certain tokens to earn a piece of protocol earnings and also liquidity mining incentives (depending on if RIP-1 and RIP-3 are passed). Below are the tokens that are eligible for rewards which are distributed proportionally to each user's deposit. However, if an eligible LP token is deposited, then the user will receive a 2.5x boost.

x1 rewards: $RGT x2.5 rewards: UNI-LP: $RGT - ETH

In order to receive these rewards, the tokens must be locked up for six month epochs.

Additionally, I suggest for a further proposal that can explore the following mechanisms with staking:

• Using Rari Pool Tokens (REPT, RYPT, RSPT) instead of ETH against RGT for rewards
  • Cannot currently support this without undergoing significant arbitrage
• Payouts in $RGT instead of earnings
• Vesting schedule implementation instead of timelock
• Using this capital to insure protocol users (users not being risk-free earners)

Motivation: This increases retention in the protocol and rewards people for staking their RGT independently, and also their Uniswap LP shares (further incentivizing liquidity for RGT).