Added Quaternion.FromMatrix
Added a Diagonal and Trace property to all matrices
Added missing doc comments in the matrix classes to reduce the number of compiler warnings
Added Quaterniond version of FromMatrix
Merge pull request #15 from GoldBlockGames/master

Implemented Quaternion.FromMatrix
.NET 4.0
Security fixes for .NET 4.0
Merge branch 'master' of https://github.com/FUSEEProjectTeam/opentk