Tests for matrix properties and special matrices

A Matrix class provides methods that can be used to check common matrix properties and special matrices:

These methods never raise errors, they just return True or False.

• is_diagonal() -> Diagonality
• is_null() -> Nullity. Inverse of bool(matrix).
• is_orthogonal() -> Orthogonality
• is_square() -> Squareness
• is_symmetric() -> Symmetry
• is_skew_symetric() -> Skew-symmetry
• Triangularity: Implemented as three methods:
  • is_upper_triangular()
  • is_lower_triangular()
  • is_triangular()
• is_unit() -> Identity/Unit matrix
• staticmethod is_conformable(m1, m2) -> Conformability.