Adding .editorconfig to help enforce whitespace rules

(and to stop me keep adding too many blank lines at the
end of files)

.editorconfig

@@ -0,0 +1,14 @@
+# http://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{py,rst,ini}]
+indent_style = space
+indent_size = 4
+