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/scope.js

@@ -92,8 +92,8 @@ SymbolDef.prototype = {
 
 AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
     options = defaults(options, {
+        cache: null,
         screw_ie8: true,
-        cache: null
     });
 
     // pass 1: setup scope chaining and handle definitions
@@ -398,12 +398,12 @@ AST_Symbol.DEFMETHOD("global", function(){
 
 AST_Toplevel.DEFMETHOD("_default_mangler_options", function(options){
     return defaults(options, {
-        except      : [],
         eval        : false,
+        except      : [],
+        keep_fnames : false,
+        screw_ie8   : true,
         sort        : false, // Ignored. Flag retained for backwards compatibility.
         toplevel    : false,
-        screw_ie8   : true,
-        keep_fnames : false
     });
 });
 
@@ -576,12 +576,12 @@ var base54 = (function() {
 
 AST_Toplevel.DEFMETHOD("scope_warnings", function(options){
     options = defaults(options, {
-        undeclared       : false, // this makes a lot of noise
-        unreferenced     : true,
         assign_to_global : true,
+        eval             : true,
         func_arguments   : true,
         nested_defuns    : true,
-        eval             : true
+        undeclared       : false, // this makes a lot of noise
+        unreferenced     : true,
     });
     var tw = new TreeWalker(function(node){
         if (options.undeclared