Qibo

First Qibo stable release.

Major Features
- Basic circuit model containing gates and/or measurements (Circuit).
- Circuits that can be executed on multiple devices such as CPU/GPUs (DistributedCircuit).
- Circuit implementing the Quantum Fourier Transform (QFT).
- Variational Quantum Eigensolver (VQE), with support for optimization of the variational parameters.
- Quantum Approximate Optimization Algorithm (QAOA), with support for optimization of the variation parameters.
- Unitary time evolution of quantum states under a Hamiltonian (StateEvolution).
- Adiabatic time evolution of quantum states, with support for optimization of the scheduling function (AdiabaticEvolution).

Documentation cleanup, further optimization.

Pre-release for testing.

Pre-release for testing.
- adiabatic evolution algorithms
- code optimization and acceleration
- advanced tutorials and examples
- linux wheels are compiled with CUDA 10.1 and manylinux2010 support.

Pre-release for testing.
- multi-gpu support
- single package with cuda10.2 and cpu-only support
- new hamiltonian overloading operators
- decomposition of multi-controlled X gates
- options to set default simulation precision, backend and device
- enhanced interface for gate matrices
- pylint errors fixed
- fixed checks for custom operators

Linux wheels are compiled with CUDA 10.2 support.

Pre-release for internal testing.