Netqasm

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- Added support for choosing the measurement basis for M-type EPR generation.
- Added the ability to manually create a Register in the SDK. Further use with these Registers is limited for now.
- Added interfaces for applications and the runtime environment, to make it easier to instantiate and run apps.
- Added the `netqasm qne login` and `netqasm qne logout` commands.

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- Renamed `Executioner` to `Executor`.
- Fixed NV compilation when doing sequential EPR create commands.

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- Removed the QST (qubit state) field from log entries.
- The QGR (qubit groups) field now contains a dict of *all* qubit groups in the whole simulation,
so also of qubits not directly acted on in the current logged operation.
- Added the `StructuredMessage` class in the SDK, which distinguishes between a header and the payload.
- Added `send_structured` and `recv_structured` functions to the `Socket` class for communication `StructuredMessage`s.
- Added `send_silent` and `recv_silent` functions to the `Socket` class for sending standard messages
that are not logged to the `<role>_class_comm.yaml` files.
- Added `sim_states` module to the SDK with some helper functions for dealing with NetSquid (only works with the `netsquid`
backend).
- Added the `--log-to-files` CLI parameter. If `True`, no logs are written to any files.
- The `Depolarise` NoiseType for network links now always generates general mixed states, instead of either a perfect
state or a fully mixed state.
- Added a `DiscreteDepolarise` NoiseType for network links that has the old behavior of `Depolarise`.
- Log directories and Python cache files are not anymore copied from the `teleport` example when creating using
`netqasm new` or `netqasm init`.
- `netqasm new` and `netqasm init` now also create a `results_config.json` file.
- Added support for more accurate NV simulation. A `nv.yaml` file can be used additionally to the `network.yaml` file.
- The BB84 example was changed to use Create and Keep entanglement generation.
- Added `results_config.json` to the `bb84` and `teleport` examples.
- Fixed bugs in CLI unit test.
- Fixed a bug related to vritual address allocation.

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- Fixed a bug where the `EPRSocket` would return an incorrect `min_fidelity` value.

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- Added `return_arrays` argument to the `NetQASMConnection` constructor.
When `False`, no arrays are returned at the end of a subroutine, even if they are used in that subroutine.
- The NV compiler now moves a qubit (if any) from the electron to the carbon before generating another entangled qubit.
- Added a `mov` instruction to the vanilla flavour. For now only used by the NV compiler, and is not in the SDK.

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- Added preliminary documentation, including a quickstart and information about the SDK.
Build it locally using `make build` from within the `docs` directory.
- Added `netqasm new` and `netqasm init` commands.
- Internal restructuring of modules.
- Logging and configuration formats are now described as dataclasses in `netqasm.runtime.interface`.
- Added more results to the BB84 application output.
- Distinguish between 'Measure Directly' and 'Create and Keep' types of entanglement in the network log.
- Fixes regarding entanglement logging and qubit group calculation.
- Instruction log files now again use the role name instead of the node name.
- Made array IDs, EPR socket IDs and node IDs `int32` instead of `uint32` such that they can be stored in registers.
- Added `min_fidelity` to EPR socket.