Fix issue with dragging pieces in Crazyhouse

[ksthicke]

Purpose

Fixes #254 by preventing default when starting to drag. Don't ask me why this fixed it -- I have no idea.

I also removed a couple relevant console.log statements that were polluting the console.

Pre-merge TODOs and Checks

• PGN file loads correctly
• Navigating through the move history works
• Starting the engine shows moves (test for both sides)
• Selecting a different variant loads a new board with the variant and you can make moves on the board
• In Crazyhouse the pocket pieces are shown and you can drop pieces

[QueensGambit]

Great. Thanks a lot for fixing this issue!