Re-instate local builds

.github/workflows/build-plugin.yml

@@ -0,0 +1,71 @@
+name: Build VCV Rack Plugin
+on: [push, pull_request]
+
+env:
+  rack-sdk-version: 2.1.0
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  build:
+    name: ${{ matrix.config.os }}
+    runs-on: ${{ matrix.config.os }}
+    strategy:
+      matrix:
+        config:
+          - os: ubuntu-latest
+            arch: lin
+            compiler: cc
+            install-dependencies: |
+              sudo apt-get update && sudo apt-get install -y libglu-dev
+          - os: macos-latest
+            arch: mac
+            compiler: cc
+            install-dependencies: |
+              brew install mesa
+          - os: windows-latest
+            arch: win
+            compiler: gcc
+            install-dependencies: |
+              choco install --no-progress -y zip
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install Rack SDK
+        run: |
+          curl -o sdk.zip https://vcvrack.com/downloads/Rack-SDK-${{ env.rack-sdk-version }}-${{ matrix.config.arch }}.zip
+          unzip sdk.zip
+      - name: Install Dependencies
+        run: |
+          ${{ matrix.config.install-dependencies }}
+      - name: Build
+        env:
+          RACK_DIR: Rack-SDK
+          CC: ${{ matrix.config.compiler }}
+        run: |
+          make dist
+      - name: Upload artifact
+        uses: actions/upload-artifact@v2
+        with:
+          path: dist
+          name: ${{ matrix.config.arch }}.zip
+
+  publish:
+    name: Publish plugin
+    runs-on: ubuntu-18.04
+    needs: build
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          path: _artifacts
+      - uses: "marvinpinto/action-automatic-releases@latest"
+        with:
+          repo_token: "${{ secrets.GITHUB_TOKEN }}"
+          automatic_release_tag: "latest"
+          prerelease: true
+          title: "Development Build"
+          files: |          
+            _artifacts/**/*.vcvplugin