* Have BrokerageModel determine default benchmark
* Add DefaultBenchmark to Python wrapper
* Handle Null benchmark case
* Add NullBenchmarkRegressionAlgorithm
* Refactor solution to have BrokerageModel return IBenchmark; also refactor QCAlgorithm benchmark handling
* Always create a new security for benchmark
* Drop security overload, Always create a new security for benchmark
* Check our securities for a symbol matching the ticker before creating a new one
* No Python version of this regression
* Address review
* Create shared SecurityBenchmark creator function
* Add Python regression and needed FuncBenchmark constructor
The `NullReferenceException` type is intended to only be thrown by the CLR.
In most cases, it should be converted to an `ArgumentException` or an
`InvalidOperationException`, depending on if the null value is a parameter
to the current method or not.
The `Exception` type should never really be thrown as it doesn't provide any
additional information or hints as to the issue. It also forces users that
would like to handle expected exceptions to catch all exceptions. These are
converted to an exception type that more accurately describes the reason for
raising the exception: `KeyNotFoundException`, `InvalidOperationException`
Colton Sellers