Rotation matrices not required to be orthonormal

[ben-congram]

• The reproject function called in lgmath::se3::Transformation's constructor (and other spots) is conditioned on det(C) = 1 but this is not a sufficient check to determine if C is in SO(3)
• Therefore, users could create a Transformation with C_ab_ = diag(2,0.5,1), for example
• Even when constructed properly, round-off error can stack up in rare cases if matrix is never forcibly reprojected
• May want to add check that C^T * C = 1, if computationally feasible