add .editorconfig

.editorconfig

@@ -0,0 +1,20 @@
+# http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# utf8, unix-style newlines, no end of file newline, no trailing whitespaces
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = false
+trim_trailing_whitespace = true
+
+# 4 space indentation
+[*.{py,c,cc,cpp,h,hpp}]
+indent_style = space
+indent_size = 4
+
+# tab indentation (no size specified)
+[Makefile]
+indent_style = tab