Lowercase variables for .Site.Params

Variables under .Site.Params are accessed with all lower-case identifiers. Hugo won't find them with an upper-case first letter, regardless of how they're formatted in the site `config` file.

Replace `template` call with the `partial` call (new in Hugo v0.12)
for including partial templates

Conflicts:
	layouts/_default/list.html

CSS is now split into poole.css and hyde.css; chrome/sidebar.html updated.

Also cherry-pick:

  * poole/hyde@48b9d1f - Set a max-width for images