Expose Xml documentation

Close #677.

There are two versions of `getXmlDocBySignature`, one uses Visual Studio services and the other uses XDocument and external files.

This PR mistakenly includes the other PR. I will rebase when the other gets merged.
The space is good, but why do we have first 1 space, then 2 spaces for all the following lines? And this happens consistently for all the functions documentations in the module.

Maybe you should always add a space for the first line only?