mathlib3

7807f3d3 - chore(linear_algebra/affine_space/basic): split (#4767)

chore(linear_algebra/affine_space/basic): split (#4767) * Split `linear_algebra/affine_space/basic` into two files: `affine_map` and `affine_subspace`. * Move notation `affine_space` to the bottom of `algebra/add_torsor`.