again, could write just one row below the bottom of output
change opencl-dev to use full extent
update opencl-dev to do full 2d convolution
add sampling kernel
convolve: perform reflection sampling inside convolution kernel
update convolution to work with multiple simultaneous filters
start to write a Level1 class
support offset data in convolve
use single workspace buffer in level1 transform
start to think about specifying level1 output nicely
get level 1 working entirely in OpenCL