Add alias to aspect-ratio values

[robsonsobral]

I could be useful to have alias for the most common aspect ratios:

• 16:9:
  • HD video
  • HDTV
  • Sixteen-by-Nine
  • Sixteen-Nine
  • Sixteen-to-Nine
• 37:20:
  • widescreen
• 4:3
  • Standard Monitor
  • TVs
  • Four-Three
  • Four-by-Three
  • Four-to-Three
• 3:2:
  • Classic Film
• 21:9:
  • Cinemascope
• 1:1
  • square
• 2:1
• 64:27

There's a list on wikipedia

[robsonsobral]

1.4142857 : 1 is the aspect ratio of ISO 216 paper sizes.