Use ePutStrLn for output in the interactive test
Add unsafeInterleaveIO to keep the initial process handle chunk from getting stuck in Threads.hs
Eliminate (ProcessHandle -> b) argument to readProcessInterleaved
Make the exception type SomeException instead of Either AsyncException IOError
Flush stderr after writing to it in ePutStrLn
No, we need to use hPutStrLn stderr to be sure of getting the final outputs in Interactive.hs
Catch exceptions in Ready.hs and inser them into the output stream
Tweaks of uses of unsafeInterleaveIO