MELPA recipe changes for one canvas technique

[rexim]

Subtask of #41
#41 introduces MELPA recipe changes. But #41 is not finalized yet. That means these changes are going to change (changes change haha) in the future. I'm going to keep track of them in the comments of this ticket.

[rexim]

#217 introduces sprites/*.txt files that should be a part of the game distro.

[rexim]

Wait a second! I can actually keep track of them in the Cask file! ._.