Velocity API (Velocity v0.6.2.2): Change sprite constructor parameters to instead use a dictionary of values (for easier serialization on disk).

[RSC-Games]

Doing this will allow scenes to be stored in plain-text form as well as source-code form. Source code scenes are more compact and faster to load, but serialized scenes are easier to store and edit on the fly. Additionally, they do not have to be cleverly parsed to be used. See #13