Add support for GitHub Actions. Remove Travis CI integration

Author: veikkos

.github/workflows/build.yml

@@ -0,0 +1,31 @@
+name: Build
+
+on: [push]
+
+env:
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: ["ubuntu-latest"]
+
+    runs-on: ${{matrix.os}}
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Install dependencies (Ubuntu)
+      if: runner.os == 'Linux'
+      run: |
+        sudo apt-get update
+        sudo apt-get install libsdl2-dev fpc
+        git clone https://github.com/ev1313/Pascal-SDL-2-Headers
+
+    - name: Build
+      run: fpc -Mtp -Fu./Pascal-SDL-2-Headers/ SJ3.PAS
+
+    defaults:
+      run:
+        shell: bash