multiple menu-items (not just the 'create' menu-group).
Moved all the main menu/context menu generation implementation in the
'menu' javascript menu.
In this implementation, if more than one menu-items specify same type
of categories, they will be created withing that group, otherwise - it
will be created separately (unless 'single' property of that category is
set to true).
We can also provide icon, priority, separator(s) above/below it for the
individual sub-menu too using pgAdmin.Browser.add_menu_category
function(...).
(lazy loading) using the require.js. This allows us to load the
javascript required for any node, only when it was loaded in the browser
tree. Also, introduced the mechanism to show/edit/create of any node in
a tab panel (wcDocker.Panel).
Modules may now include functions that return lists of menu items
that will be included on the main browser window menu. While we're
at it, move the test views into a separate module.
