Get conversion

Created by: Durman

Problem statement

Next strings are quite inefficient. https://github.com/nortikin/sverchok/blob/89b770b3b27805d85ba2f83f569a0e0897692ccc/core/socket_conversions.py#L237-L238

In my test tree it takes aobut 0.6% of the whole tree execution. For comparison the conversion itself took the same time. I assume the the lines should not take any time if convert the tests attribute into a dictionary, like this:

class DefaultImplicitConversionPolicy(NoImplicitConversionPolicy):
    conversion = {'v': {'m': quaternions_to_matrices, 'c': vector_to_color},
                  'm': {'v': matrices_to_vectors, 'q': matrices_to_quaternions},
                  ...
                  }