Switch to my fork of metalsmih-templates

This brings additional support for overriding template blocks from content files, ala Hyde (+Jinja) style templating.
Generalize page banner CSS
Slideshow

Shuffle around slides, add controls for slideshow, add extra styles for alternate dark background by quadrants.
Slideshows 2

Switch to/use MicroEvent instead of Smokesignals for events in slideshow.
Mobile menu fixes

Fix mobile menu overlay with slides on index page, and other page elements.