Added missing equal and notEqual with epsilon for quaternion types to GTC_quaternion

Added EXT_matrix_relational: equal and notEqual with epsilon for matrix types

Added missing vec1 based constructors

Added identity functions #765

Added separated performance tests (to finish)

Clarified refract valid range of the indices of refraction, between -1 and 1 inclusively #806

kotlin 1.3.61

lwjgl 3.2.3

gradle 6.0.1

shadow plugin 5.2.0

kotlintest 3.4.2