Update python_easy_chess_gui.py

* Add adviser engine. User can get an advise thru a short pv, shown in adviser box. Engine adviser setting can only be accessed in neutral mode and only hash, threads and movetime are settable. Default adviser engine is the first engine found in the engine list.
* Do not show engine id name in the box.
* Set default movetime to 5sec was 2sec.
* Update code comments.
* Revert color of button text to black after returning from Play to Neutral mode. These text buttons will change color to green or red in Play mode.

Closes #22

Author: fsmosca