examples of usage with the important unu commands

make "unu make" into a nrrd function

enable the unu 2op and 3op operations that output integers to save
the output as, say, signed char, instead of float.  This is different
than being able to change input type, for operations like "gt".

----- Teem 1.5beta1 cut-off -----

----- Teem 1.5 cut-off -----

figure out why I was getting a MIO (memory in use) error with 
unu resample when I had the bug in nrrdAlloc_nva (where the
axes sizes were never actually set, so they were both zero).

make darn sure that nobody uses printf(), only fprintf()

standardize and document use of special single characters
for meaning as unrrdu arguments:
M : max position along an axis, equal to #samples-1
# : ?
- : standard in and standard out
any others?
