Automatically work out required '/assembliesUnderTest' paths from the test csproj file

[ceddlyburge]

At the moment you have to specify a list of space separated strings in the '/assembliesUnderTest' command line parameter to GenerateCodeFromExcelTest.exe.

These are then scanned by the framework, to find interfaces that match definitions in the Excel tests.

It would probably be better to work these requirements out automatically, by looking at the dependencies in the csproj file. This would cause it to be a bit slower, and might cause confusion if there were interfaces with the same name in different namespaces, but this slight annoyance is probably less than the annoyance of having to edit the '/assembliesUnderTest' command line parameter.

We should have a think about it first though, to make sure that the assumption holds true.