Optimized particles being added to a simulation.

If the mass is 0, you don't need to sort

.github/workflows/ci.yaml

@@ -0,0 +1,27 @@
+name: spacerocks
+on:
+  push:
+    branches: ['v3']
+
+# jobs:
+#   build:
+#     strategy:
+#       matrix:
+#         os: ['ubuntu-latest', 'macos-latest']
+#         python-version: [3.10, 3.11, 3.12]
+#     runs-on: ${{ matrix.os }}
+#     steps:
+
+#       - name: Checkout
+#         uses: actions/checkout@v3
+
+#       - name: Set up Python ${{ matrix.python-version }}
+#         uses: actions/setup-python@v1
+#         with:
+#           python-version: ${{ matrix.python-version }}
+
+#       - name: Get cspice
+#         uses: mstksg/get-package@v1
+#         with:
+#           brew: libomp llvm
+#           apt-get: libomp-dev