fix various spelling errors

__tests__/PolynomialInterestSetter.test.ts

@@ -182,7 +182,7 @@ describe('PolynomialInterestSetter', () => {
     expect(maxAPR2).toEqual(newAPR);
   });
 
-  it('Fails to deploy contracts whose coefficients dont add to 100', async () => {
+  it("Fails to deploy contracts whose coefficients don't add to 100", async () => {
     await expectThrow(
       solo.contracts.testPolynomialInterestSetter.methods.createNew({
         maxAPR: '0',

contracts/external/oracles/DaiPriceOracle.sol

@@ -189,7 +189,7 @@ contract DaiPriceOracle is
 
     /**
      * Gets the USD price of DAI that this contract will move towards when updated. This price is
-     * not bounded by the varaibles governing the maximum deviation from the old price.
+     * not bounded by the variables governing the maximum deviation from the old price.
      */
     function getTargetPrice()
         public

contracts/external/proxies/PayableProxyForSoloMargin.sol

@@ -71,7 +71,7 @@ contract PayableProxyForSoloMargin is
     {
         require( // coverage-disable-line
             msg.sender == address(WETH),
-            "Cannot recieve ETH"
+            "Cannot receive ETH"
         );
     }
 

contracts/protocol/SoloMargin.sol

@@ -31,7 +31,7 @@ import { Storage } from "./lib/Storage.sol";
  * @title SoloMargin
  * @author dYdX
  *
- * Main contract that inherets from other contracts
+ * Main contract that inherits from other contracts
  */
 contract SoloMargin is
     State,

contracts/protocol/interfaces/IErc20.sol

@@ -23,7 +23,7 @@ pragma solidity 0.5.7;
  * @author dYdX
  *
  * Interface for using ERC20 Tokens. We have to use a special interface to call ERC20 functions so
- * that we dont automatically revert when calling non-compliant tokens that have no return value for
+ * that we don't automatically revert when calling non-compliant tokens that have no return value for
  * transfer(), transferFrom(), or approve().
  */
 interface IErc20 {

contracts/protocol/lib/Token.sol

@@ -164,7 +164,7 @@ library Token {
                 returnValue := mload(0x0)
             }
 
-            // not sure what was returned: dont mark as success
+            // not sure what was returned: don't mark as success
             default { }
         }