test net reshaping
include Reshape in caffe time

Since we are now calling Reshape in the Forward pass, it's only fair to
include it when timing. Reshape calls should normally be four or so
orders of magnitude faster than Forward calls; this change also makes it
easy to notice a mistake that causes something slow to happen in
Reshape.
add Net::Reshape for only reshaping

Note that it is not normally necessary to call this function when using
reshapable nets, but sometimes it can be useful to compute the sizes of
intermediate layers without waiting for the forward pass.
[pycaffe] expose Net::Reshape
[docs] clarify the use of Blob::Reshape a bit
check that LRN's local_size is odd as the current implementation requires