Proposal of Selector TF

[Jeffxz]

We currently have a few issues reported are related to selector

https://github.com/w3c/publishingcg/issues?q=is%3Aissue+is%3Aopen+label%3A%22selector+or+annotation%22
And I have filed issue here w3c/web-annotation#448

The selector is apparently base of quite a few higher level spec/feature such as annotation, media overlay and maybe anything would related to mapping something else to certain fragment (text or part of image) of html document.

The reason I would like to start this as TF is to see if anyone would be interested in working on selector as well since it's widely related to other feature. And I need help with drafting document.

A short term goal would be to draft a tech report.