Complete set of magic methods

[Pierre Denis]

Lea provides support for some functions like abs and divmod, by overloading associated dunder methods:

>>> abs(vals(-2, -2, 0, 2))
0 : 0.25
2 : 0.75
>>> divmod(vals(0, 1, 2, 3), vals(1, 2))
(0, 0) : 0.25
(0, 1) : 0.125
(1, 0) : 0.25
(1, 1) : 0.125
(2, 0) : 0.125
(3, 0) : 0.125

However, several methods are not implemented, like floor, ceil, etc. Also, the shift operators are not supported.

Lea should implement these, to be more consistent.

[Pierre Denis]

Implement missing dunder methods (refs #93)

→ <<cset 1980706dee71>>