Price Oracle of Swap.Pet, support SwapPet/Uniswap/SushiSwap/ChainLink ...

Price Oracle of Swap.Pet include price refer and swap.

the swapper is for swap the target base token to quote token at realtime.

on Swap.Pet, default quote token is pUSDT(pegging USDT).

Goals of this new architecture are:

1. swap more than refer.
2. Scalability.
3. Reduce costs by minimizing number of ethereum transactions and operations performed on-chain.
4. Increase reliability during periods of network congestion
5. Reduce latency to react to price changes

Currently two main modules:

1. [refer]:refer price of market.
2. [swapper]:the price which can swap on at realtime.

in app dir:$ npx npm i swap-pet-price-oracle

in sol file:import "swap-pet-price-oracle/contracts/SwapPetOracle.sol";

mkdir ~/defiApp
cd defiApp
npm init
npm install --save-dev hardhat
npm install --save-dev @nomiclabs/hardhat-truffle5 @nomiclabs/hardhat-web3 web3

edit config:$ vi hardhat.config.js

add gas-reporter:$ npx npm install -D eth-gas-reporter get gas report:$ npx truffle test add coverage:$ npx npm install -D @nomiclabs/buidler solidity-coverage get coverage:$ npx truffle run coverage run ganache :$ npx ganache-cli --deterministic compile:$ npx hardhat compile test:$ npx hardhat test accounts:$ npx hardhat accounts account balance:$ npx hardhat balance --account 0xFABB0ac...