Rendering initial map state on grid (follow-up to #268): 3 points

[nataliavelez]

The initial grid state should be populated with Players and Items from the types and positions parsed from a CSV file, if provided, instead a spawning algorithm.

[nataliavelez]

@jessesnyder @alecpm Sorry, I forgot which task you're each taking on first - are there any other details I should add for this ticket?

@jessesnyder merged in code from a year ago that does # 268 and #269. So this is ready for deployment.