XML documentation report

[Jericho]

Analyze XML documentation included with each addin and generate a report to suggest improvements.

See cake-build/website#318 for details

[Jericho]

Slowly but surely making progress. I can now generate a report that looks like this:

However, I am now facing a problem that I had previously avoided:

Most likely these exceptions are due to decorated methods that return a type which is defined in a different assembly than the one being analyzed. I had previously avoided this issue by carefully ensuring I did not cause types to be instantiated: https://github.com/cake-contrib/Cake.AddinDiscoverer/blob/develop/Source/Cake.AddinDiscoverer/Steps/AnalyzeNuGetMetadataStep.cs#L345

I will have to investigate how I can avoid types to be instantiated in my XML documentation analysis code.

[Jericho]

Following Skype call with @pascalberger, we agreed that AddinDiscoverer will analyze as many addins as possible and will output a message such as "We were unable to analyse the XML documentation for this addin because ..." if there are any issues related to not being able to load a dependent assembly, or any other problem.