Add CI with Github Actions

Check for compatibility with all version of Emacs since Emacs 25.1

Add Cask file for managing dependencies in CI

Add badge in README for CI

.github/workflows/workflow.yml

@@ -0,0 +1,46 @@
+name: CI
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  check-compatibility:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        emacs_version:
+          - 25.1
+          - 25.2
+          - 25.3
+          - 26.1
+          - 26.2
+          - 26.3
+          - 27.1
+          - 27.2
+          - 28.1
+          - snapshot
+    steps:
+      - uses: actions/checkout@v3
+      - uses: purcell/setup-emacs@master
+        with:
+          version: ${{ matrix.emacs_version }}
+      - uses: actions/cache@v2
+        id: cache-cask-packages
+        with:
+          path: .cask
+          key: cache-cask-packages-000
+      - uses: actions/cache@v2
+        id: cache-cask-executable
+        with:
+          path: ~/.cask
+          key: cache-cask-executable-000
+      - name: "Cask setup"
+        uses: cask/setup-cask@master
+        if: steps.cask-cache-executable.outputs.cache-hit != 'true'
+      - name: "Install Cask dependencies"
+        run: cask install
+        if: steps.cask-cache-executable.outputs.cache-hit != 'true'
+      - name: "Check version compatibility"
+        run: make all