Support for Tensorflow 2.2

Improved temporal pattern code: Correctly handle non-normalized input…

…s and linear activation functions; implement low-precision activations; more efficient computation of the number of ops.

PyTorch support

v0.4.1

Updated docs.

SpiNNaker support

v0.4.0

Updated changelog.rst for new release (SpiNNaker support).

Brian2 extensions

v0.3.2

Releasing 0.3.2 (Brian2 extensions).

Loihi support

v0.3.1

Releasing 0.3.2 (Brian2 extensions).