Add default and example color scheme objects to colors.json.

Minify colors.json in build_data.js. Add colors.json to DataLoaderSystem's fileMap.

Add color scheme helper functions to StyleSytem, with comments to describe each functions parameters and return values (where applicable).

Update StyleSystem's styleMatch() function to interact with color scheme objects from colors.json rather than from STYLE_DECLARATIONS.

Fix white space discrepancies in StyleSystem.

Update color_selection.js and colorblind_mode_options.js to use StyleSystem rather than the non-existent ColorSystem.

Uncomment color schemes and colorblind mode options sections in preferences.js to add them to the Preferences pane of the UI.

Refs: Issue facebook#1230

Extract the style definitions to a separate folder, including style definitions which were in colors.json.

Add abstracted color and style definitions to minification and data loading files.

Load the style definitions alongside color loading in StyleSystem.js.

Update style selectors to use newly abstracted style definitions.

Map colors defined in the color system to their hex codes. in StyleSystem.js.

Reduce the boilerplate code in style matching in StyleSystem.js.

Add default color scheme property to StyleSystem.js to hold the default color scheme loaded from color_schemes.json.

Abstract out HEX color code determination in styleMatch() into its own function, getHexColorCode.

Define getHexColorCode() such that it fetches the HEX color code from the default color scheme if it is not defined in the current color scheme to increase efficiency and reduce the amount of information that has to be defined in a new color scheme object.

Optimize color scheme definitions in color_schemes.json to utilize the performance upgrade in getHexColorCode() by removing key-value pairs already in the default color scheme.

Add another example colorblind-friendly color scheme.

Correct spelling mistake in helper function description.

NOTE: Also includes rebasing merge conflict handling

Add `showColorblindSimulators` to the array of poweruser features.

Add strings for the `showColorblindSimulators` feature in the poweruser pop-up to `core.yaml`.

Add `_initHide` property to `section.js` to enable initializing any section `<div>` with a `.hide` class in a non-permanent manner.

Call the `initHide()` function with D3.js chaining to set the `_initHide` property of the to `true`, which means that `uiSectionColorblindModeOptions` section should initially be hidden.

Add custom on-toggle behavior for `showColorblindSimulators` feature such that the state of the poweruser feature checkbox associated with it adds or removes the `.hide` class from the section's `<div>`.