Pyqt-fit

- Removed reference to npy_float128. Seems it doesn't work on 32 bits machines.
- Adapted to 32 bits machines
- Changed integration from basic to Simpson's method
- If cython is not present (on not wanted!), kernels exist also as pure python
functions
- Free switching between pure python and cython kernels
- Cython 1.19 is not really needed, so downgrading the need to 1.17
- Moved Cython dependencies into an "extra" with name 'Cython'

- Added transformed KDE class, to compute KDE using variable change

- Correct CDF of tricube kernel (error inducing a 1e-4 error on CDF computation)
- Added tests for kernels
- Added new interface for 1D local polynomial -- compatible with previous one!
- User can specify their own design matrix to allow for non-polynomial basis

- Added Epanechnikov kernel
- plot_residual_tests now supports nD regression
- corrected kde in case no method is specified
- corrected grid_eval (now works)
- corrected weights application

- Added tests for the various modules
- Corrected bug in sharedmem for Python 3
- Now using print_function and relative_import futures to minimise changes between Python 2 and 3

- Corrected Cython import error in kernels.py
- Added "from __future__ import division" in all numerical module