Converted OpenGl tutorials to F#.

• Silk.NET
  • 12 out of 13 tutorials (omitted model loading)
• OpenTK
  • Chapter 1: all 9 tutorials
  • Chapter 2 maybe in the future...

F# features:

• Tried to keep to functional principals (no mutable if not necessary, no classes)
• Result computational-expression
• Units of measure for degrees and radians