Fix whitespace, add .editorconfig, add GitHub workflow

.editorconfig

@@ -0,0 +1,11 @@
+# https://EditorConfig.org
+
+# Top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file, utf-8 charset
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8

.github/workflows/editorconfig.yml

@@ -0,0 +1,14 @@
+name: EditorConfig Checker
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  editorconfig:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v3
+      - uses: editorconfig-checker/action-editorconfig-checker@main
+      - run: editorconfig-checker