#1 Add lenght() functionality

[Jeremy Jones]

Add the following methods to queue and network interfaces:

length():
"""return the number of items in the queue in all states"""

length_put():
"""return the number of items in the queue in the put
state"""

length_avail():
"""return he number of items in the queue in the avail
state"""

length_rqstd():
"""return he number of items in the queue in the rqstd
state"""