Perturbed recombination implemented

One flag has been added: 'has_perturbed_recombination'. Set to 0, you
recover the previous CLASS behaviour, and set to 1, the proper
perturbed recombination is computed.

Note, the ndf15 file has been modified so that the function
'perturb_print_variables' prints the evolution at each time step, and
not only on the boundaries as it used to be the case.
Removed ALL trailing whitespaces. Please do not put them back
Classy has separated headers and contents + typos for ne and Neff

Beginning of a major change in the classy wrapper. It now consists of
two files, classy.pyx and cclassy.pxd, the last containing all the
headers definition. The long term goal is to generate these two files
(or at least a good portion of these two files) automatically.
bug of Neff reverted: it was fine !
classy: corrected Neff, added Omega_n and Neff to be accessed from likelihoods
Merge branch 'devel' of github.com:baudren/class into devel

* 'devel' of github.com:baudren/class:
  classy: corrected Neff, added Omega_n and Neff to be accessed from likelihoods
cosmetic changes for easier automatic wrapping
further cleaning for wrapping
added changes of jesus; does compile
jesus changes work apart from popen() on my mac
command line works on lppc
working and cleaned!
added tensors in external_Pk
added option to write primordial spectra in output
minor presentation details related to jesus
included changes from jesus in december: tenors work with external_Pk
First version of automatic interface generator

The goal is still far ahead, lots of work needs to be done, and testing. But,
so far, the script reads class.h, extract the name of the modules, read their
header file, create the classy.pyx with the proper fields, create wrapper
around the init function.

It essentially should create a low-level interface to CLASS, allowing for
writing a new version of the wrapper, in pure Python, that will not need to be
recompile every time we change it, should be much more readable and
user-friendly. Most importantly, this means that in the long term, any change
to the CLASS source code will be retransmitted to the wrapper seamlessly,
without human intervention (or so one can hope).
indented perturbations
indented perturbations
fixing conflicts for merging