Add feature to allow user to install an engine

[fsmosca]

• Add sub menu "Manage" under engine menu.
  • Add submenu "Install" under Manage
  • Add submenu "Edit" under Manage
  • Add submenu "Delete" under Manageoption values.
• Add code for Install
• Add code for Edit
• Add code for delete
• Load the engine if it would work.
  • Set Engine Opponent
  • Set Engine Adviser