Typography and glyphs updates

Typography:

• Updated typography ramp, classes, mixins, and functions.
• Added typography controls (headings, subheadings, paragraphs, and captions).

Glyphs:

• Changed glyph names to be more semantic.
• Added glyph function to get a glyph's unicode value.
• Changed "icon" to "glyph."
• Changed glyphs docs to be generated using JSON.

Other changes:

• Added Navbar component.
• Updated Dropdown control.