Overhaul WEC subscription formatting

[ralish]

This PR may be more substantial than desired and so you choose to decline this, but that's fine, I'm only submitting these PRs in case they're of interest upstream. The commit history should be fairly clear, but in short, there's zero functional changes. Instead, the sample WEC subscriptions have had their formatting substantially overhauled to be IMO far more readable and maintainable. There's particular emphasis on the embedded XPath queries which now have consistent formatting with splitting over multiple lines and appropriate indentation. This makes parsing and editing them far easier, not to mention spotting errors which may not necessarily be syntactic (as in PR https://github.com/iadgov/Event-Forwarding-Guidance/pull/2).

In addition, I've renamed the subscription files to have more accurate & verbose file names (I don't see why they need to be short) and removed all the samples/* subscriptions. I'm unclear what their purpose is and a diff between them and the NT6/* subscriptions shows only very minor changes. The NT6/* samples appear to be newer, and the changes don't suggest they're for supporting downlevel OSs, so in the absence of a compelling reason to keep them they've been removed.

Comments welcome.

[iadgovuser1]

We'll take a look at the changes. We'll likely accept the majority of these changes. Thanks.

[philkloose]

I like the reorg suggestions, but I will say that I appreciate the "Targets:" information in the Description field of each subscription.

[iadgovuser1]

We are going to revisit this since we need to update this for Windows 10. I think we will generally end up accepting most of the pull request. We just haven't decided what we are going to keep versus not keep and the main author hasn't been available to help make that determination.