Add some declarations and features for Matrix class

[Kaiser-Yang]

Those declarations below should be added:

• A new constructor to construct an identity matrix
• A new constructor to construct a diagonal matrix
• A new method calculating the matrix exponentiation
• Add all the friend functions' decalarations into mca.h

Those features below should be added:

• A new method to check if a matrix is symmetric with single thread
• A new method to check if a matrix is antisymmetric with single thread