TEST: ReferenceHost stores error objects when exception thrown.

Currently the nested pipelines have the error objects but the main
pipeline does not have access to them. So the pipeline.Error in the
ReferenceHost is always empty with Pash. Windows PowerShell does
populate the pipeline.Error with objects sent to WriteError by a
cmdlet.
Report compilation errors when using Add-Type

All compilation errors are written to error stream and are available
via the $error variable.
The Add-Type cmdlet is terminated if there are compilation errors.

There are some problems here. Pash currently only shows the error in
the console from the exception that terminates the cmdlet.
PowerShell shows the exception error and all the compilation errors.
The error from the exception results in a duplicate error record. If
the cmdlet is changed so it does not terminate with an exception then
the compiler errors are displayed in the console.