Rewrite the Gantt chart. #6276 This version of the Gantt chart supports nested charts. So Projects, Versions, and Issues will be nested underneath their parents correctly. Additional features: * Move all Gantt code to Redmine::Helpers::Gantt class instead of having it in the Gantt class, controller, and view * Recursive and nest sub-projects * Recursive and nest versions * Recursive and nest issues * Draw a line showing when a Project is active and it's progress * Draw a line showing when a Version is active and it's progress * Show a version's % complete * Change the color of Projects, Versions, and Issues if they are late or behind schedule * Added Project#start_date and #due_date * Added Project#completed_percent * Use a mini-gravatar on the Gantt chart * Added tests for the Gantt rendering git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4072 e93f8b46-1217-0410-a6f0-8f06a7374b81