Add .editorconfig

.editorconfig

@@ -0,0 +1,19 @@
+# http://editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[**.{h,cc,mm,m}]
+indent_style = space
+indent_size = 2
+
+[*.{md,markdown}]
+trim_trailing_whitespace = false
+
+# Makefiles always use tabs for indentation
+[Makefile]
+indent_style = tab