Fix jsdoc
Restore ol.interaction.Select options
Remove stray option in modify-features example
Add a way to delete vertices with the Modify interaction

After this change, vertices can be deleted by simply clicking on
them. This is the same behaviour as e.g. in geojson.io.
Lower pixel tolerance to avoid accidental vertex deltion
Updates to pass jshint validation
Scale the text offset by the device's pixel ratio

Fixes #1918
Merge pull request #1283 from ahocevar/delete-vertex

Add a way to delete vertices with the Modify interaction
Merge pull request #1915 from twpayne/select-interaction

Restore select interaction behaviour
Merge pull request #1921 from fredj/text-offset

Scale the text offset by the device's pixel ratio
Fix initial state of the Modify interaction

Features that are in the features collection need to be added to the R-Tree.
Create the R-Tree in the Modify constructor

In this way features can be added/removed to/from the R-Tree even when the interaction does not have a map.
Make the Modify interaction more robust

This prevents a JavaScript error when features are added while the interaction does not have a map.
Merge pull request #1922 from elemoine/modify

Fixes to modify interaction
Update node packages

 * closure-util - Driving the compiler, not watching spurious files
 * async - Bugfixes not related to our use, but this may sidestep the Travis errors we're seeing
Merge pull request #1917 from tschaub/node-deps

Update node packages.