Use consistent line endings

This re-uses the configuration used on the Public Archive to ensure
consistent line endings are used everywhere: store LF on the Git repo,
and let Windows users manage the conversion to CR LF themselves.

.editorconfig

@@ -0,0 +1,21 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = space
+trim_trailing_whitespace = true
+
+[*.txt]
+indent_size = 3
+
+[*.{html,xml,md}]
+indent_size = 2
+
+[*.json]
+indent_size = 4
+
+[*.md]
+# Allow 2 spaces at the end of a line to cause a line break
+trim_trailing_whitespace = false

.gitattributes

@@ -0,0 +1 @@
+* text=auto