UI subsystem

[Goshido]

It's needed to develop UI subsystem. The core technologies should be:

• HTML5
• CSS
• FreeType

Main goal is to make browser as UI developing tool.

Steps

• [x] HTML parser
• [x] CSS parser
• [x] HTML + CSS validator tool
• [x] HTML validator tool documentation
• [x] UI system documentation
  • [x] UILayer documentation
  • [x] TextUIElement documentation
  • [x] DIVUIElement documentation
  • [x] ImageUIElement documentation
• [x] Scriptable UI
• [x] UI rendering backend
  • [x] FreeType setup
  • [x] Font atlas
  • [x] Append layout constraints
  • [x] Render UI