Failing introspection with wildcards on matrices / remove M.I

[nthiery]

Example:

    sage: M = random_matrix(QQ, 3,4)
    sage: M.*row*?
    ArithmeticError
    ...
    sage.matrix.matrix_rational_dense.Matrix_rational_dense.inverse (build/cythonized/sage/matrix/matrix_rational_dense.c:8519)()
    717         """
    718         if self._nrows != self._ncols:
--> 719             raise ArithmeticError("self must be a square matrix")
    720 
    721         if self._nrows == 0:

    ArithmeticError: self must be a square matrix

Analysis: M has an attribute I which is supposed to evaluate to the inverse of M. When ipython does its introspection to recover the list of attributes of M with M.*row*?, that attribute is evaluated. Which triggers an error since M is not square.

Proposed solution: remove M.I that was deprecated two years ago in #20904 .

[nthiery]

M.I was actually removed in #26647. Testing now whether introspection works. If yes, I'll close the ticket as resolved.

[nthiery]

sage: M = random_matrix(QQ, 3,4)
sage: M.*row*?
M.add_multiple_of_row
M.automorphisms_of_rows_and_columns
M.delete_rows
M.dense_rows
M.linear_combination_of_rows
M.matrix_from_rows

So this works now. Cool!