Fix: Switched LESS mixins to use `;`

• Switched our custom LESS mixins to use `;` instead of `,` for parameter lists.
	» This from the LESS docs sums it up best: “Parameters are either semicolon or comma separated. It is recommended to use semicolon. The symbol comma has double meaning: it can be interpreted either as a mixin parameters separator or css list separator.”
Minor: Changed `screenheight-` to `vh-`

• Changed the `.generate-screenheights()` call to create classes with the prefix `vh-` (formerly the default of `screenheight-`).
	» Newer CSS3 supports a `vh` unit which is exactly this— 100vh is the viewport's height.  So we might as well use the same naming for our class.
	» It's nice and short too.
	• Updated index.html with the changed class names.
Skrollr + Emummy gfx = Parallaxing stars

• Installed `skrollr`, `skrollr-stylesheets`, and `skrollr-ie` with bower.
	» Each now in the bower_components/ dir.
	• Each, at their current versions, added to bower.json's dependencies.
	• Set up index.html for Skrollr:
		◦ Added `<script src…>`es for `skrollr.stylesheets.min.js`,  `skrollr.min.js`, and (conditional-comment wrapped)  `skrollr.ie.min.js`.
		◦ Added skrollr init JS after includes with a sole `edgeStrategy: 'ease'` option.
		◦ Added `data-skrollr-stylesheet` attribute to `styles.css` <link>.
• Each of the `#starfield*` <div>s now has an inner class `back image` <div> so that the `background` CSS property (inner) can ease separately from the `opacity` CSS property (outer).
	• Moved background-image and background-repeat CSS into `.image` descendent selectors.
	• Changed `.phase > .back` CSS to also apply to `.phase > .back .back`.
	• Added `fixed` to the background CSS— moving relative to screen-stationary looks more convincing.
• Added opacity animations to each of the `#starfield*` elements and background-position animations to eacb of the `#starfield* > .image`s.
	» Smaller stars start visible, with larger stars coming in towards the end.
	» Since the parallaxing can give away the star layers, made the large star graphics (2 and 3) move close in speed to each other.
	• Made a simple `-skrollr-dry-animation(…, { … })` mixin to create both the `-skrollr-animation-name: …;` and `@-skrollr-keyframes … { … }` CSS in one go, with the same animation name.
		» “Don't Repeat Yourself”.
• Fix: `!important` on html/body's `height: 100%`.
	» Skrollr weirdly adds an explicit pixel height to the <body> tag's style attribute, which messes up our positioning.

Also:
• Changed the sky-phase gradient to go from cobalt-darker to blue-darker rather the reverse.
	» With the stars appearing it looks better to have it transition darker, like night fall.
Fix: Mobile scrolling

• Turned off skrollr's mobile support by supplying a `mobileCheck` config option which always returns false.
	» Skrollr's mobile solution sucks— the scrolling feels linear and uncomfortable, causes a bunch of other layout issues (white margin on right, #title-phase collapses), and its doesn't work with fixed-attachment backgrounds.  There are better ways to solve this.
	» Currently works great for iOS 8; in iOS ≤7, just jumps the scroll position after the release glide has settled to a stop (the same issues encountered with playground.6.slippyd.com).
Added Google webfonts

• Added the recommended <link> tag to index.html for Google-hosted fonts Oswald, Indie Flower, and Dancing Script.
• Added a `monologue` class to main.less styled to 50px Dancing Script.
	• Added the `monologue` class to each of the monologue text <divs> in index.html.