Refactor, silence flake8 messages

Update python_easy_chess_gui.py

Fix a bug in OS determination

Fix issue #39

Refactor Timer initialization

v1.0 release candidate 1

* Add feature to save a game to white repertoire or black repertoire files. Closes #27
* Add icons to boxes. Closes #28
* Creates engines config file called pecg_engines.json file automatically. It reads the Engine folder of uci engines and build the config file. Closes #8
* Add feature to install uci engines. Closes #11
* Add Time Control. Closes #33
* Add tool to delete player from PGN file. This is primarily intended for smaller files only of around 1000 games or less as it may take some time to process. Closes #32
* Add feature to save user names. This name is also used in the game saved in pgn file.

Update README.md