Add includeBlunder argument (solves #16)

[karol-brejna-i]

My proposal for dealing with omitting the blunder move (initial move of the puzzle) --solves #16 .

1. Puzzle generation stays untouched
2. Blunder move removal happens when exporting the puzzle to PGN
3. Move exporting a puzzle to PGN to a dedicated class (PgnExporter).

I am wondering if we shouldn't invert the logic (meaning) of the argument: having something like skipBlunder instead of includeBlunder. Then we could have simpler construction, like ./main.py --skipBlunder

[karol-brejna-i]

Some additional changes sneaked in:

1. Silencing the UCI engine (logging.getLogger("chess._engine").setLevel(logging.WARNING))
2. Small readme fix
3. Removal of unused args in opening_counter.py

[vitogit]

Excellent work. thanks!
Just waiting if you want to delete the opening file, then I will merge

[vitogit]

I am wondering if we shouldn't invert the logic (meaning) of the argument: having something like skipBlunder instead of includeBlunder. Then we could have simpler construction, like ./main.py --skipBlunder

I think we can have shorthands for the params, like -sb to skip blunder or just -s, -q for the quiet param, etc

[vitogit]

I opened a ticket in case we want to change how the arguments works #22