TOSA specification v0.80.0 Release Notes

Change specification to refer to signless types consistently.
    RESCALE takes new arguments to determine whether inputs and outputs are unsigned
Add ERF activation function
Improve conformance definitions for floating-point operations
    New flag for convolution operators to determine accuracy requirements
Add stateful operators - VARIABLE / VARIABLE_READ / VARIABLE_WRITE
Add DIM operator to allow for improved shape inference calculations
Allow bias tensors to be broadcast
Various other cleanup, see the git revision history for complete details