Rename and alias basic functions

[mikeheddes]

I think it would be nice if we rename the hypervector creation function to remove _hv because I don't think that is necessary since the normal names don't interfere with any functions and the name is still clear.

In addition I think we should alias the hypervector creation and operation functions in the root of the library:

import torchhd

x = torchhd.random(2, 10000)
torchhd.level(2, 10000)
torchhd.circular(2, 10000)

torchhd.bind(x[0], x[1])
torchhd.bundle(x[0], x[1])
torchhd.permute(x[1])

[mikeheddes]

Update: we won't rename but will add the alias