Add an .editorconfig file

This helps contributors get the basic formatting options in their IDEs
automatically set right. (The setting for PHP files complies to the
PSR-12 standard.)

This change does not autoformat any files with these settings, though.

Author: oliverklee

.editorconfig

@@ -0,0 +1,34 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# PHP files
+[*.php]
+indent_style = space
+indent_size = 4
+
+# MD files
+[*.md]
+indent_style = space
+indent_size = 4
+
+# XML files
+[*.xml]
+indent_style = space
+indent_size = 4
+
+# YAML files
+[*.{yml,yaml}]
+indent_style = space
+indent_size = 2
+
+# JSON files
+[*.json]
+indent_style = space
+indent_size = 4

.gitattributes

@@ -1,3 +1,4 @@
+/.editorconfig export-ignore
 /.gitattributes export-ignore
 /.github/ export-ignore
 /.gitignore export-ignore