Added different color transfer functions
Added different color transfer functions

Implementation of:
1) https://www.researchgate.net/publication/220518215_Color_Transfer_between_Images
(or https://www.cs.tau.ac.il/~turkel/imagepapers/ColorTransfer.pdf) in "logarithmic Lαβ" colorspace;
2) https://github.com/jrosebr1/color_transfer in LAB, RGB, HSL and XYZ colorspaces.
Second is probably not fully correct:
HSL transfer makes wrong colors, LAB on some images does too.
Haven't figured out yet how to fix them.
VaKonS/neural-style