Add GitHub actions and LuaCheck (#12)

* Add GitHub actions and LuaCheck

* Fix LuaCheck warnings

.github/workflows/build.yml

@@ -0,0 +1,16 @@
+name: build
+on: [push, pull_request]
+
+jobs:
+  luacheck:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install Luarocks
+      run: |
+        sudo apt-get update -qyy
+        sudo apt-get install luarocks -qyy
+    - name: Install Luacheck
+      run: luarocks install --local luacheck
+    - name: Run Luacheck
+      run: $HOME/.luarocks/bin/luacheck .

.luacheckrc

@@ -0,0 +1,21 @@
+unused_args = false
+allow_defined_top = true
+max_line_length = 999
+
+globals = {
+    "ctf", "minetest",
+    "irc", "ctf_playertag",
+    "gauges",
+}
+
+read_globals = {
+    string = {fields = {"split", "trim"}},
+    table = {fields = {"copy", "getn"}},
+
+    "ctf_stats", 
+    "filter",
+}
+
+files["server_chat/staff_channel.lua"].read_globals = { "table" }
+files["spectator_mode/init.lua"].globals = { "ctf_map" }
+files["spectator_mode/init.lua"].ignore = { "player" }