Fix proof caching to speed up tests

[Arinerron]

When I generate a proof, verify (successfully) from Solidity, and then verify again, it fail the second time for some reason.

To reproduce it, uncomment this line, and try to run the tests:

zkerc20/lib/proofGeneration.js

Line 58 in 0e405a5

//return this.proofCache[cacheKey]; // XXX: somehow verifyProof knows if it's been verified before

Note how I'm deploying all new contracts (including the verifier contract) before each test:

zkerc20/test/integration/api-test.js

Line 36 in 0e405a5

beforeEach(async function() {

I also tried hardhat_reset.

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Once this is fixed, I just need to

• Uncomment this line:

  zkerc20/lib/proofGeneration.js

  Line 58 in 0e405a5

  //return this.proofCache[cacheKey]; // XXX: somehow verifyProof knows if it's been verified before

• Use a better hash function for the cache key haha

  zkerc20/lib/proofGeneration.js

  Lines 51 to 52 in 0e405a5

  	// TODO: use a better hash function lol
  	const hashCode = s => s.split('').reduce((a,b)=>{a=((a<<5)-a)+b.charCodeAt(0);return a&a},0)