Add Matrix#deconstruct and Vector#deconstruct ([Feature #21675] Advent of Pattern Matching)

[der-scheme]

Adds pattern matching support to Matrix and Vector, which can be used to extract features and enforce certain constraints.

Usage

m =  Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]]  # => Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
m in Matrix[[a, 2, 3], [4, b, 6], [7, 8, c]]  # => true
diagonal = [a, b, c]                          # => [1, 5, 9]
diagonal.sum == m.trace                       # => true

vec =  Vector[1, 2, 4, 5, 3]  # => Vector[1, 2, 4, 5, 3]
vec in Vector[1, 2, *ff , 3]  # => true
ff                            # => [4, 5]

[marcandre]

LGTM 👍