nprof: estimate parameters for noise profiling

this output module fits a gaussian/poissonian noise model and creates noise profile files to be stored in ~/.config/vkdt/nprof or data/nprof/ and read back in by vkdt.

parameters

test set the noise profile parameters in the file written out in the i-raw:main module for inspection
install install the noise profile to the home directory

connectors

input the single-channel ui32 noise profile data from the raw histogram