Basic vector code, without a coordinate system class

All calculations essentially occur in the same frame.
i, j, k and x, y, z are imported as base vectors and base scalars by default on importing sympy.vector.
delop is a Del operator instance.

Example:

>>> v = 3*i - j
>>> delop ^ v
0

(delop ^ v represents curl of v)
Theres a problem with calling <code>\_\_new\_\_</code> the way you suggest. Its that Dummy, the super class whose corresponding method is called, accepts only a name.
In any case, the args to <code>\_\_new\_\_</code> will get better and more descriptive, and 'uniquely identify' the instance once CoordSysRect is implemented. I am doing that in my next PR. This PR is to have the basic vector framework stable and working, or rather to ensure that all basic vector operations occur without fault. Moreover, the hashing and eq functions, as far as I see, aren't particularly inefficient.
But I agree with your point of the args being an exact identification for the instance. Maybe adding the name to the 'id' would clear this conceptual confusion?