Enhance glm::dualquat and singular value decomposition for square matrix

[Yun Yang]

Dual quaternion and SVD for mat3 are commonly used in computer graphics and robotics.

Although glm has offered the basic functionality for dualquat, some features are still missing

• convertion between plucker coordinate and dual quaternion
• the conjugate/dual conjugate/combined conjugate for dual quaternion
• norm/normalize/normalized methods for dual quaternion
• sclerp of the dual quaternion
• more details at dual_quaternions

SVD for mat2/mat3/mat4 are missing, especially the mat3, which is commonly used for physics simulation

• one can refer the implementation to svd_glsl