This allows for setting the passive socket's SO_RCVBUF. Option works
similarly to the current sendbufsize configuration option.
* Change how recveive_data() works
When reading data from the socket for passive transfers to the server,
receive_data() now works very similar to send_data_with_read(). Reads
from the network are now done using either the filesystem block size or
the configuration option readsize chunks.
* Crank version.h
[Changes discussed with lukem.]