sort options in alphabetical order (#1743)

They started off as functional groups I guess, but given the sheer number of options this is becoming too difficult to read.

lib/propmangle.js

@@ -62,12 +62,12 @@ function find_builtins() {
 
 function mangle_properties(ast, options) {
     options = defaults(options, {
-        reserved : null,
-        cache : null,
-        only_cache : false,
-        regex : null,
-        ignore_quoted : false,
-        debug : false
+        cache: null,
+        debug: false,
+        ignore_quoted: false,
+        only_cache: false,
+        regex: null,
+        reserved: null,
     });
 
     var reserved = options.reserved;