Make file objects deal properly with unnamed pipes
Add create_pipe function to file object API
Reorder some functions
Adapt to changed pipe_create signature
Add get_file_flags function
Refactor file object log messages

Add a signature and expand macro to produce the signature of a file object
without open coding the logic over and over again.
Refactor file object seek handling for pipes
Add flags parameter to create_pipe function to control non-blocking behavior

If a pipe is used as stdin for a process object then its read and should
have normal blocking behavior. But its write end has to be non-blocking
otherwise redapid cannot write to it without the risk of blocking the
whole daemon.
Lower two error messages to warnings
Update API sketch
Add test to upload and execute the weather station Python example