Fixing processes connected by files

When processes were connected by files, the reading process could finish
before the write process terminates.

To fix that, when a process wants to read from a file, first it checks
if the file has some data and if someone is using it.

If ok, the process reads it.

If someone is writing, we use rb-inotify to watch the file. When if
finishes, we unblock the reading process.

That guarantees consistency ^_^
New feature, new version