Tensor analysis package.
This is a separate version of what_we_commited_to_sympy.
Consists of:
Arraypy class - N-dimentional arrays
TensorArray class - N-dimentional array with contravariant and covariant indicies.
Classes declared in arraypy.py file.

There is also modules:
1) tensor_methods.py       - Tensor algebra.
2) tensor_fields.py        - operation in tensor fields like diff, rot, lie, etc...
3) riemannian_geometry.py  - tensor operations about some riemannian geometry, ok?
4) helper_functions.py     - some help functions.

Additional info will be later.