Fix bug in ScannerParameters.code().
Delete unused code.
Refactoring to introduce MatchedRequest and MatchedReply interfaces.
Introduce minimum server version expectation into engine, so that we
don't need lots of server version check logic (as seen in the Java version).
Improve server dumping so it won't re-dump replies of the same type it
has already dumped. This speeds up dumping if receiving option chains
etc.
Fix bug in engine where connection not being closed. This was causing
tests to reach the 8 concurrent client limit in IB Gateway.
Gracefully handle end of stream rather than panic and recover.
Engine should deliver errors to every known observer.
Error handling should recognise warning level messages and not treat
them as fatal.
Improve server dumping so it includes the client ID.
Clarify in comment the version number is for TWS API, not TWS.
Engine test to verify time set.
Fix date parsing to reflect what IB Gateway is sending as of server
version 70.
Options tests to be skipped when in "go test -short" mode, therefore
eliminating the need for IB market data subscriptions (as per edemo /
demouser IB Gateway login).