page load: Make initializations more explicit.

We now initialize most modules in ui_init.js, which
isn't the perfect place to do it, but at least now
we have a mostly consolidated entry point.

All the new foo.initialize() methods introduced in
this module run the same order relative to each
other as before this commit. (I did some console
logging with a hacked version of the program to
get the order right.)  They happen a bit later than
before, though.

A couple modules still have the `$(function() {`
idiom for miscellaneous reasons:

       archive - is a different bundle
       common - used elsewhere
       list_render - non-standard code style
       scroll_bar - no exports
       setup - probably special?
       socket - $(function () is nested!
       transmit - coupled to socket
       translations - i18n is a bigger problem
       ui_init - this bootstraps everything

static/js/overlays.js

@@ -189,7 +189,7 @@ exports.open_settings = function () {
     });
 };
 
-$(function () {
+exports.initialize = function () {
     $("body").on("click", ".overlay, .overlay .exit", function (e) {
         var $target = $(e.target);
 
@@ -209,7 +209,7 @@ $(function () {
         e.preventDefault();
         e.stopPropagation();
     });
-});
+};
 
 return exports;