Add GitHub Action to build with CMake on Windows, Linux and macOS.

.github/workflows/build.cmake

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+if("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
+    execute_process(COMMAND "${CMAKE_COMMAND}" --build "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            --config $ENV{BUILD_TYPE}
+
+            RESULT_VARIABLE result
+            )
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Linux")
+    execute_process(COMMAND "${CMAKE_COMMAND}" --build "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            -- -j 3
+
+            RESULT_VARIABLE result
+            )
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Darwin")
+    execute_process(COMMAND "${CMAKE_COMMAND}" --build "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            --config $ENV{BUILD_TYPE}
+            -- -j 5
+
+            RESULT_VARIABLE result
+            )
+endif()
+
+if(NOT result EQUAL 0)
+    message(FATAL_ERROR "CMake returned bad exit status")
+endif()

.github/workflows/build_cmake.yml

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+name: CMake Build
+
+on: [ push, pull_request ]
+
+env:
+  # Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ windows-latest, ubuntu-latest, macos-latest ]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Prerequisites
+        run: cmake -P ${{ github.workspace }}/.github/workflows/install_prerequisites.cmake
+
+      - name: Configure CMake
+        run: cmake -P ${{ github.workspace }}/.github/workflows/configure.cmake
+
+      - name: Build
+        run: cmake -P ${{ github.workspace }}/.github/workflows/build.cmake
+
+      - name: Package
+        run: cmake -P ${{ github.workspace }}/.github/workflows/package.cmake
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: ${{ matrix.os }}
+          path: package/projectM-*

.github/workflows/configure.cmake

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+if("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
+    execute_process(COMMAND "${CMAKE_COMMAND}"
+            -G "Visual Studio 16 2019"
+            -A "X64"
+            -S "$ENV{GITHUB_WORKSPACE}"
+            -B "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            -DTARGET_TRIPLET=x64-windows
+            -DCMAKE_VERBOSE_MAKEFILE=YES
+            "-DCMAKE_INSTALL_PREFIX=$ENV{GITHUB_WORKSPACE}/cmake-install"
+            "-DCMAKE_TOOLCHAIN_FILE=$ENV{VCPKG_INSTALLATION_ROOT}/scripts/buildsystems/vcpkg.cmake"
+
+            RESULT_VARIABLE result
+            )
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Linux")
+    execute_process(COMMAND "${CMAKE_COMMAND}"
+            -G "Unix Makefiles"
+            -S "$ENV{GITHUB_WORKSPACE}"
+            -B "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            -DCMAKE_VERBOSE_MAKEFILE=YES
+            -DCMAKE_BUILD_TYPE=$ENV{BUILD_TYPE}
+            "-DCMAKE_INSTALL_PREFIX=$ENV{GITHUB_WORKSPACE}/cmake-install"
+
+            RESULT_VARIABLE result
+            )
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Darwin")
+    execute_process(COMMAND "${CMAKE_COMMAND}"
+            -G "Unix Makefiles"
+            -S "$ENV{GITHUB_WORKSPACE}"
+            -B "$ENV{GITHUB_WORKSPACE}/cmake-build"
+            -DCMAKE_VERBOSE_MAKEFILE=YES
+            "-DCMAKE_INSTALL_PREFIX=$ENV{GITHUB_WORKSPACE}/cmake-install"
+
+            RESULT_VARIABLE result
+            )
+endif()
+
+if(NOT result EQUAL 0)
+    message(FATAL_ERROR "CMake returned bad exit status")
+endif()

.github/workflows/install_prerequisites.cmake

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+message(STATUS "Using host CMake version: ${CMAKE_VERSION}")
+
+if("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
+    # On Windows, using vcpkg to install and build is the best practice.
+    set(VCPKG "$ENV{VCPKG_INSTALLATION_ROOT}/vcpkg.exe")
+    execute_process(COMMAND "${VCPKG}" --triplet=x64-windows install glew sdl2
+
+            RESULT_VARIABLE result
+            )
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Linux")
+    # On Ubuntu, installing the required dev packages is sufficient
+    message(STATUS "Updating apt package sources")
+    execute_process(COMMAND sudo apt-get update
+            COMMAND sudo apt-get -f install
+
+            RESULT_VARIABLE result
+            )
+
+    if(NOT result EQUAL 0)
+        message(FATAL_ERROR "Could not update apt package lists")
+    endif()
+
+    execute_process(COMMAND sudo apt-get install
+            libgl1-mesa-dev
+            mesa-common-dev
+            libsdl2-dev
+            libglm-dev
+            qtbase5-dev
+            llvm-dev
+            libvisual-0.4-dev
+            libjack-jackd2-dev
+
+            RESULT_VARIABLE result
+            )
+
+elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Darwin")
+    # macOS uses Homebrew to install additional software packages.
+    execute_process(COMMAND brew update
+            COMMAND brew install sdl2
+
+            RESULT_VARIABLE result
+            )
+endif()
+
+if(NOT result EQUAL 0)
+    message(FATAL_ERROR "A command returned bad exit status")
+endif()

.github/workflows/package.cmake

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+if("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
+    execute_process(COMMAND "${CMAKE_CPACK_COMMAND}"
+            -G ZIP
+            --config "$ENV{GITHUB_WORKSPACE}/cmake-build/CPackConfig.cmake"
+            -B "$ENV{GITHUB_WORKSPACE}/package"
+
+            RESULT_VARIABLE result
+            )
+else("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Linux")
+    execute_process(COMMAND "${CMAKE_CPACK_COMMAND}"
+            -G TGZ
+            --config "$ENV{GITHUB_WORKSPACE}/cmake-build/CPackConfig.cmake"
+            -B "$ENV{GITHUB_WORKSPACE}/package"
+
+            RESULT_VARIABLE result
+            )
+endif()
+
+if(NOT result EQUAL 0)
+    message(FATAL_ERROR "CPack returned bad exit status")
+endif()