Feature/more tools

This PR will make minor fixes and improvements to the new tool/events/selection system, as well as add some new tools based upon it. 

* [x] polygon selection overly
* [x] polygon selection tool
* [x] lasso selection tool
* [x] axis wheel zoom
* [x] axis pan 
* [x] pinch zoom
* [x] minor fixes to touch interactions (buttons require two taps, e.g.)
* [x] user guide docs for new tools

That's alot of tasks for one PR. The reason I want to tackle all this in one place is because I want to make sure everything works together harmoniously and that the experience of adding several tools here can be used to help make adding tools in general a more reasonable and well-defined process.