Add GitHub CI

.github/workflows/ci.yml

@@ -0,0 +1,69 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        rust:
+        - nightly
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install rust (${{ matrix.rust }})
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.rust }}
+          profile: minimal
+          override: true
+
+      - name: Enable Cargo cache
+        uses: Swatinem/rust-cache@v2
+
+      - name: Build
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: ${{ matrix.features }}
+
+      - name: Test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: ${{ matrix.features }}
+
+      # fails to build:
+      #- name: Doc
+      #  uses: actions-rs/cargo@v1
+      #  with:
+      #    command: doc
+      #    args: ${{ matrix.features }}
+
+  fmt:
+    name: Check formatting
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          components: rustfmt
+          profile: minimal
+          override: true
+
+      - name: cargo fmt -- --check
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: -- --check
+