kbin-code-highlighting: Adds support for code syntax highlighting to kbin.

Uses HLJS to add syntax highlighting to kbin.

• 0.1 - Initial launch, basic support with singular theme.
• 0.2 - Update to remove unnecessary code.
• 0.3 - Add support for stylesheet URLs to be specified in settings and to be stored in memory.
• 0.3.1 - Added support for numerous kbin instances.
• 0.4 - Preloads a dropdown with predefined stylesheets for ease of use. Reworked how stylesheets are stored. Added header for code sections that displays what language code section is in (unless poster specifies, this is best-guess based on HLJS). Added clipboard copy button and made code section collapsible.

Example, 0.1 - PowerShell
Example, 0.3 - Side by side
Example, 0.4 - JavaScript
Example, 0.4 - New functionality
Example, 0.4 - Settings and themes