Improve Image Galleries on Tools

[petelandvt]

There is now a carousel of thumbnails with a "click to enlarge" button (which opens an overlay slideshow of the original images, with captions, via the Colorbox plugin)

[petelandvt]

I've improved the navigation arrows for both carousels (home page features and tool page image gallery). They are always present on the screen for the tool image gallery, and appear on hover only for the home page features (which plays a slideshow automatically).

I also noticed that the "click to enlarge" feature (which brings up the original images in an overlay slideshow) was not working on phones... it should be working for all displays now.