bugfix to ccv_sample_up

previous implementation was taken from OpenCV, and it deals with
imperfect upsampling, for w*h image, it upsamples to (2w-1)x(2h-1).
In that case, the Gaussian weight should be G(0.0) G(1.0), G(0.5) G(0.5)
For perfect upsampling, i.e. wxh => 2wx2h, the actual Gaussian weight
should be G(0.25) G(1.25), G(0.25) G(0.75)
correcting Gaussian weight & unit test

I got it wrong the first time, variance for upsampling should always be
0.5
have a pretty good part filter initialization now
refactored a bit for easier dev later
intermit commit, the original dpm training result is promising. fixed a
compilation error in Mac OSX with kiss_fft
dpmcreate now can run

but need more work to make sure it produces correct result
added regression test

added regression tests. it is a test set for actual bugs, thus, any of
them is one defect that once existed in the code base.
clean up test code
a "wow" error in ccv_dense_matrix_renew

ccv_dense_matrix_renew is an old function. It meant to check whether
the pass-in matrix is on specification, if it is, sign it and return,
if it is not, create/retrieve a new one based on the signature and
return. However, I made a huge mistake by not check if signature is
empty or not, and by the signature generation process, it will generate
a non-empty signature for pass-in empty ones, and using this one
to retrieve matrix from cache. Since I don't use that much
empty-signature matrix myself, the problem hasn't surfaced until
when I have to regularly ccv_make_matrix_mutable/immutable for
dpm implementations.
sometimes you just need a fresh eye
code reorganize for release

1. slice out hog/canny to ccv_classic.c;
2. almost done with dpmcreate;
3. add two test case for ccv_filter (concern about centre point).
fix an error in growth factor of ccv_array
small tweaks on training process
ccv_cache_cleanup a bug
it finally works!
some cleanup work ahead
this is the usable dpmcreate binary
be able to resume work again
new trained pedestrian model and new dpmcreate
reworked the bbfcreate cli to match dpmcreate one