Add an editorconfig file.

.editorconfig

@@ -0,0 +1,15 @@
+# .editorconfig, Boone, 02/11/21
+# Editor behavior settings
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[makefile]
+indent_style = tab