changes:

• made UniversalResolver significantly more stable in it's return values
• BatchGateway's errors are now documented within solidity. HTTP errors now use HttpError(tuple(uint16 status, string message)[]) to differentiate them from regular solidity errors.
• single data resolve (resolve(bytes,bytes)/etc) calls will now revert if the call was unsuccessful, rather than just returning the error data.
  • errors from the name's resolver are propagated by being wrapped with ResolverError(bytes). this makes it easier to identify when an error is coming from the UniversalResolver itself, or an external resolver.
  • batchgateway HTTP errors are propagated directly via HttpError(tuple(uint16 status, string message)[])
• batch data results from resolve are now tuple(bool success, bytes returnData), rather than just bytes
• added ResolverNotContract error for if a name's resolver is not a contract
• external resolver calls are now all checked for safety via ERC165's supportsInterface
  • this is to avoid situations where in older versions of solidity, reverts would use all the remaining gas for a call
  • this was already implemented for extended resolver capability, but now applies to all calls (excl. callbacks)
  • unsafe calls will still be attempted with a maximum of 50k gas