add run_cnet::get_pipe() to get a p_conv_pipe_t for the currently set-up network.

then, use get_pipe() in conv_pyra to avoid needing to read a
seperate/duplicate-data XML pipe file. note that get_pipe is
incomplete: it assumes that the caffe net is a simple pipeline and it
only understands pooling and conv layers. however, it does have
(untested) support for non-square pad/stride/kern_sz.

also note: (1) caffeif.H no longer include caffe headers; it wasn't
really supposed to / didn't need to. (2) we process images 1-by-1 in
conv_pyra, which was again required / sensible / the general original
intent, but didn't much matter until now.