add editorconfig and checker

.editorconfig

@@ -0,0 +1,17 @@
+# Editor configuration, see http://editorconfig.org
+root = true
+
+[*]
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+
+[*.java]
+indent_size = 4
+
+[*.md]
+max_line_length = off
+trim_trailing_whitespace = false

.pre-commit-config.yaml

@@ -18,3 +18,9 @@ repos:
     hooks:
       - id: check-travis
       - id: check-github-workflows
+  - repo: https://github.com/editorconfig-checker/editorconfig-checker.python
+    rev: 2.4.0
+    hooks:
+      - id: editorconfig-checker
+        args: ['-disable-indent-size']
+        exclude: (\.(pgm|pnm|ppm|html|eml)|quick.txt)$