Class PipeReader

Initialise a non-blocking pipe object, given a real file readfile.
timeout = the default timeout (in seconds) at which read will decide
          that there is no more data in the queue.
          timeout = None, or < 0 stands for indefinite waiting time. 
pipesize = the size (in blocks) of the queue used to buffer the
          blocks read
blocksize = the maximum block size for a raw read.

Read data from the queue, to a maximum of maxblocks (0 = infinite). Does not block.

Read data from the queue, allowing timeout seconds between block arrival. if timeout = None, then use default timeout. If timeout<0, then wait indefinitely. Returns '' if we are at the EOF, or no data turns up within the timeout. If condition is not None and condition() == False returns. Reads at most maxblocks (0 = infinite). Does not block.