Need proper call stack details on RuntimeException in python

[ganik]

Currently on exception message is printed out, like:
Error: *** System.Collections.Generic.KeyNotFoundException: ' ...

for debugging purposes call stack info is also needed, something like:

StackTrace: at System.Collections.Generic.Dictionary2.get_Item(TKey key) at Microsoft.ML.Featurizers.LagLeadOperatorDataView.Cursor.TypedColumn2.MoveNext(String grainString)
at Microsoft.ML.Featurizers.LagLeadOperatorDataView.Cursor.MoveNext()
at Microsoft.ML.DotNetBridge.Bridge.SendViewToNativeAsDataFrame(IChannel ch, EnvironmentBlock* penv, IDataView view, Dictionary`2 infos) in E:\sources\tmp\NimbusML\src\DotNetBridge\NativeDataInterop.cs:line 314
at Microsoft.ML.DotNetBridge.Bridge.RunGraphCore(EnvironmentBlock* penv, IHostEnvironment env, String graphStr, Int32 cdata, DataSourceBlock** ppdata) in E:\sources\tmp\NimbusML\src\DotNetBridge\RunGraph.cs:line 225
at Microsoft.ML.DotNetBridge.Bridge.GenericExec(EnvironmentBlock* penv, SByte* psz, Int32 cdata, DataSourceBlock** ppdata) in E:\sources\tmp\NimbusML\src\DotNetBridge\Bridge.cs:line 370