TextView output for game console output

[rmanosuthi]

A similar thing's already done with extracting mods (with threading too!), so this shouldn't be too complicated.

[rmanosuthi]

This is now implemented, with a caveat:

Proton outputs to stderr instead of stdout (??) and I can't figure out how to print stderr and stdout to the same TextView buffer, without the output delaying until the game is stopped.

For now only stderr is connected to the buffer.