Inconsitent use of Tin, Tio, Tn

[manuschneider]

In the Python bindings, the argument names for (Uni)Tensors as arguments vary more or less randomly between Tin (288 occurances), Tio (26 occurrences) and Tn (15 occurrences). It would be better to use one convention everywhere. This breaks the current API, but I could imagine that the argument names are not used much currently. It would be good to fix this for the future at least.

We could either use Tin if it is an input tensor that will not be changed and Tio if it is changed in inline functions (I did this in 2e7d5cc). Or we use Tin everywhere.

Affected files:

pybind/linalg_py.cpp
pybind/algo_py.cpp
pybind/tnalgo_py.cpp
pybind/random_py.cpp

Some cpp files also use Tn insead of Tin, but this does not affect the API at least.

[manuschneider]

I think we should decide on a convention such that it can be used correctly in the future an #680 can be adapted accordingly or merged.

[manuschneider]

I think we should fix a convention, such that #680 can be merged and #681 can be implemented in a uniform style.