remove "New" from Project menu

This removes the "New" item and also the corresponding form(s) in
index.html (new_project_dialog and new_user_dialog) since they are
not in use anymore.
Move stack menu to top level

This creates a new top level menu called "Stacks" which contains the
Project's stacks that were previously displayed under "Projects/Current".

This also makes the submenu "Projects/Open" obsolete, so projects are
now directly accessible from "Projects" menu.

Summary:
"Project/Current" -> "Stacks"
"Project/Open" -> "Project"
Allow CSS styling of menu items seperatly

This adds a div around the menu items so they can be styled seperatly from
all the other toolbar items.
Make menu entries take up less space

Remove all CSS padding from menu entries to make more space for the
tools in the top toolbar.
Merge pull request #629 from fzadow/rework-project-menu

Reorganise project menu structure