Add RelatedActivityId to the events

[markantill]

ActivityId and RelatedActivityId header fields aren't available through the API but were available in the old TraceEvent library are useful for correlating events.

[swannman]

Good catch Mark, that would be useful. If you’d be willing to submit a pull request that adds these, we’ll review and merge.

[pathtofile]

Put up a PR for ActivityID: https://github.com/microsoft/krabsetw/pull/129 Didn't touch RelatedActivityID, that's a deeper hole involving parsing extended data items

[swannman]

@pathtofile thank you! Merged #129.