changed hadamard calculation to shorter version & added tests

[hahahannes]

This PR updated the hadamard calculation to usa a shorter function and added tests for the hadamard function.

When approved, we could an automated tests from github via Github Actions. Then the tests will automatically run on every pull request and push to the master branch

# This workflow will install Python dependencies, run tests and lint with a variety of Python versions
# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions

name: Run unittests

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        python-version: [3.7, 3.8]

    steps:
    - uses: actions/checkout@v2
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v2
      with:
        python-version: ${{ matrix.python-version }}
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
    - name: Test with unittest
      run: |
        python -m unittests discover tests