Menu & settings updates

• In-progress game now saves and resumes
  • When entering the menu
  • When leaving to view another page in your web browser [note: this part of the save/resume functionality may not work properly on itch]
• New setting that allows you to turn off the animation that happens when dealing a new game
• Credits screen
• In-game instructions

Commits through 7b79be0, March 21, 2020