Removed distinction between 'acquire 1' and 'acquire N'
Changed level calibration arithmetic to 32-bit from 64-bit
Greatly simplified the command system

Instead of having to make entries in four-some files to add a command,
just add the function to any file of the form cmd/ch*c, using a comment
or three to specify the command text, parameter and identifier.
cmd-gen.py will extract these to _cmd_resouce.c and _cmd_resource.h.