allow loading maps and replays from data rather than file paths

[awestlake87]

this is especially useful for wine because it expects files to be specified using the Windows paths. loading by data also removes the expectation that the game instance has to run in the same environment as the coordinator process

[awestlake87]

it seems at least for now that loading replays from data does not work. not sure if client or server is failing, or if it's even implemented yet