Eagerpy

New Features
* `float64()` conversion (thanks eserie)
* `slogdet()` implementation (thanks eserie)
* support for `__matmul__ ` (thanks eserie)
* `topk()` implementation (thanks mglisse)

Bug Fixes
* fixed JAX array recognition (thanks zimmerrol)
* minor changes to support TensorFlow compilation (thanks eserie)

New Features

* indexing with multiple tensors now supports more cases
* massively improved docs and guides

New Features

* added `prod()`
* added development documentation
* improved the reliability of the tests
* other improvements and bug fixes

squeeze` now raises an error if a concrete axis is specified and this axis does not have length `1`

New Features

* added `sort`
* `pow` now accepts tensors for the exponent
* docs are now automatically build on GitHub

specified version numbers for dependencies