Implemented a feature that give a project and optional default context. When set,

this context will be pre-populated when creating an action from the project's page.
When creating an action from the home page, the context will be auto-selected when
the project is selected if the context field has not yet been entered.

This implementation is a combination of the great patch submitted by James Kebinger
(thanks James!) and some of my modifications and additions.

Don't forget to rake db:migrate.

Fixes #162, originally suggested by Rolf one year ago!

Also in this commit:

 * Tweaked selenium tags test
 * Tweaked formatting of next/previous project HTML
 * Implemented Null Object pattern for context to support
   a Project having no default context
 * Removed tickler.rhtml, no longer in use
 * applying z-index values to project sortable list items (otherwise context
   autocomplete was appearing below next list item)
 * Swapped order of project and context in new action form (setting default context
   makes more sense this way)
 * Removed CSS width of for form elements, so form could be used in content area
   without being too narrow
   


git-svn-id: http://www.rousette.org.uk/svn/tracks-repos/trunk@480 a4c988fc-2ded-0310-b66e-134b36920a42

tracks/app/controllers/contexts_controller.rb

@@ -162,6 +162,7 @@ class ContextsController < ApplicationController
       # Hides actions in hidden projects from context.
       @not_done_todos = @context.todos.find(:all, :conditions => ['todos.state = ?', 'active'], :order => "todos.due IS NULL, todos.due ASC, todos.created_at ASC", :include => :project)
       @count = @not_done_todos.size
+      @default_project_context_name_map = build_default_project_context_name_map(@projects).to_json
     end
 
 end