added 2D tight split direct hist

Well.. I think it's ready. It's in the splitPixelFull.pyx file. Both 1D and 2D

Btw.. The integration limits were there, in both  splitPixel and splitPixelFull 

Also the splitPixelFullLUT should be reverted to the previous version (without the 2D option), and you should pull my splitPixelFullCRS (which is how it should have been named) 

I can make a LUT version too when I get the chance


Oh!! of course testing and verification pending :)