Playing around: do the masking/trimming inside the loops.
Add checker board function for debugging
allow some pixels to be masked.
Add some comments.
Add functions and data structs to store trim bits in NIOS. Make
loops aware of trimming and masking of pixels.
Add (DEBUG) firmware version with trim-on-nios functionality.
Merge branch 'master' into trim-on-nios

Conflicts:
	software/dtb_expert/dtb_config.h
	software/dtb_expert/pixel_dtb.h
	software/dtb_expert/rpc_dtb.cc
	software/dtb_expert/trigger_loops.cpp
Update RPC interface.
Add NIOS trim bit cache for FLAG_FORCE_MASKED trigger loop mode
Add new flash file SW2.6 with NIOS trim bit cache for FLAG_FORCE_MASKED