Remove rebase conflict in README.md

Chromium users need to check Background graphics option when printing.

Add the grunt-cli as a dependency instead of assuming global grunt.

remove redundant spaces.

Fix spelling error in print-pdf plugin

prevents XSS vulnerability (see https://github.com/janl/mustache.js/pull/388)

stops parallax failing if only the single horizontal slide and multiple vertical

check for 0 division, stops parallax failing if only the single horizontal slide and multiple vertical

Update the theme README.md

Fix text being cut off in Chrome when printing.

Fixed #1379 - config keyboard now disables 's' key

Fixes #1225

always enable highlight.js to fix markdown-only usage