Add engine adviser

[fsmosca]

• [x] Create adviser button, can be a text element
• [x] Add 1 Text element to show the adviser short pv
• [x] Show short pv, once button is pressed, adviser engine will search for bestmove of the position
• [x] Create a Set Adviser Engine sub-menu under Engine menu. User can select engine name and other basic setting
• [x] Modify Engine menu, rename Set Engine sub-menu to Set Opponent Engine