Fix Bug - Promotion

[FeXd]

Promotion has been fixed by:

• changing to using js-chess-engine Option 1 with-in memory
• rather than creating a menu to pick which piece, just promote to what the puzzle wants
• this make it easier, but also will make theme-ing things later easier

URL parameters:

• you can now specify puzzle and rating via URL parameters
• examples: https://puzzlechess.ca?puzzle=0nSDR, https://puzzlechess.ca?rating=1000, https://puzzlechess.ca?puzzle=0nSDR&rating=1000
• if valid puzzle isn't found it will load random
• if rating is not a number it will default to previous

Progress on #24 in that users can change rating via parameters, but I would still like them to be able to do so using an actual interface menu.

Closes #26 Closes #25