Work around newer solidity syntax problems

The autodoc soliditydomain has an outdated solidity grammar and thus
fails on some new syntax constructs. I've worked around this for now by
slightly changing the solidity source code.
See cag/sphinxcontrib-soliditydomain#9

contracts/services/ServiceRegistry.sol

@@ -193,7 +193,7 @@ contract Deposit {
     /// @notice Withdraws the tokens that have been deposited
     /// Only `withdrawer` can call this.
     /// @param _to The address where the withdrawn tokens should go
-    function withdraw(address payable _to) external {
+    function withdraw(address to) external {
         uint256 balance = token.balanceOf(address(this));
         require(msg.sender == withdrawer, "the caller is not the withdrawer");
         require(now >= release_at || service_registry.deprecated(), "deposit not released yet");

contracts/test/HumanStandardToken.sol

@@ -65,7 +65,6 @@ contract HumanStandardToken is StandardToken {
         return true;
     }
 
-    fallback () external { revert(); }
 
     function decimals() public override view returns (uint8 decimals) {
         return _decimals;