Manager menu reorganization

The Manager's menus (as of 7.4) are kind of clunky. Here's a proposal for reorganizing them.

• File
  • Close Window
  • Exit BOINC Manager
  • Select Computer
  • Shut down connected client
  • New Window (launch another Manager)
• View
  • Notices
  • ...
  • Disk usage
  • Simple View
  • Event Log
• Activity
  • (no change)
• Options
  • Add project
  • Use account manager
  • Manager options
  • Event log options
  • Select display columns
  • Computing preferences
  • Exclusive applications
  • Read config files
• Tools
  • Run CPU benchmarks
  • Retry network communication
• Help
  • (no change)