Try to add basic CI

.github/resources/run_notebooks.x

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+#!/bin/bash
+set -eu
+export REPOROOT="$( cd -P "$( dirname "${BASH_SOURCE[0]}" )/../../" && pwd )"
+for notebookfile in `find "${REPOROOT}"/notebooks/ -name '*.ipynb'`; do
+    echo
+    echo '------------------------------------------------------'
+    bn=$(basename "${notebookfile}")
+    echo "Testing ${bn}"
+    echo "${notebookfile}"
+    rm -rf "${REPOROOT}/test_tmp_rundir"
+    mkdir "${REPOROOT}/test_tmp_rundir"
+    cd "${REPOROOT}/test_tmp_rundir"
+    echo "   .. converting to script"
+    jupyter nbconvert --to script "${notebookfile}" --output="${PWD}/${bn}_converted"
+    echo "   .. executing script"
+    time ipython ./${bn}_converted.py | cat
+done

.github/workflows/run_notebooks.yml

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+name: basictest
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '30 11 * * 2'  # 11:30 every Tuesday
+
+jobs:
+  build:
+    # The CMake configure and build commands are platform agnostic and should work equally
+    # well on Windows or Mac.  You can convert this to a matrix build if you need
+    # cross-platform coverage.
+    # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
+    strategy:
+      matrix:
+        include:
+           #Note: Python 3.13 works (Aug 2024) because of the
+           #"allow-prereleases: true" below.
+          - { os: ubuntu-latest, python: '3.10' }
+          - { os: ubuntu-latest, python: '3.11' }
+          - { os: ubuntu-latest, python: '3.13' }
+          - { os: macos-latest,  python: "3.12" }
+    name: ${{ matrix.os }}.${{ matrix.CC }}.python-${{ matrix.python }}
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        path: src
+
+    - name: Setup python
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python }}
+        allow-prereleases: true #Needed (Aug 2024) for Python 3.13.
+
+    - name: Pip install
+      run: |
+        set -eux
+        python3 -m pip install numpy matplotlib spglib ase gemmi jupyterlab ipympl
+        python3 -m pip install ncrystal>=3.9.4
+        #python3 -m pip install pymatgen
+
+    - name: Check versions
+      run: |
+        set -eux
+        which python3
+        python3 --version
+        which cmake
+        cmake --version
+        nctool --version
+        ncrystal-config -s
+
+    - name: Launch tests
+      run: |
+        set -eu
+        ./src/.github/resources/run_notebooks.x