@0x/types: Add FillResults, MatchedFillResults, and

`BatchMatchedFillResults` types.
`@0x/contracts-utils`: Add reference functions for `SafeMath`.
`@0x/contracts-exchange-libs`: Add reference functions for `LibMath` and
`LibFillResults`.
`@0x/contracts-test-utils`: Move `*FillResults` types to `@0x/types`.
`@0x/contracts-test-utils`: Add `log_utils.ts`.
`@0x/contracts-test-utils`: Add `hexRandom()` to `hex_utils.ts`.
`@0x/contracts-test-utils`: Add the contstants: `MAX_UINT256`,
`ADDRESS_LENGTH`.

contracts/utils/src/index.ts

@@ -1,2 +1,5 @@
 export * from './artifacts';
 export * from './wrappers';
+
+import * as reference_functions from './reference_functions';
+export import ReferenceFunctions = reference_functions;