init of model sum in GUI level of vistrails
add prefix name to model
clean up functions
add quadratic model
add doc for parameters
add more tests
add fit function on a list of x,y
Merge pull request #186 from licode/model_sum

Model sum
API : removed function that was too clever

bin_image_to_1D was far to clever for the benefit it provided.

It alleviated the need to make one call at the cost of adding
a function with took a function as an argument and needed
to be able to blind-pass dictionary of kwargs through.  This
is a nightmare for wrapping at vistrails and difficult to
document or debug for API-usage.
Merge pull request #190 from tacaswell/remove_image_to_1D

API : removed function that was too clever
BUG: fixed the raius_to_twotheta for the mistake
changed it to np.arctan(radius / dist_sample) from 2*np.arctan(radius / dist_sample)