original sprite assets

[jmorwick]

need to stop relying on private "mwsu-assets" repo and develop initial set of original sprites for mwsu game

Must include:

• grass
• floor
• wall
• door
• player
• guide
• shopkeeper
• countertop
• chest
• key

initial set should be expanded to about two dozen sprites. Any additions should be noted on this issue.

[jmorwick]

57409232300a5354d521d735c0ea59333496fe76 contained:

• grass
• key
• floor (external)
• wall
• door (external)
• chest
• guide
• player

still needed:

• shopkeeper
• countertop
• door (internal)
• floor (internal)

[jmorwick]

name sprites according to standard:

https://github.com/mwsu-csmp/gg-pixi-client/wiki/Texture-Mapping-Standard