Purpose
If an argument is given, resets RED FRAMENO to this value,
causing the next image taken to have this number. Without an
argument, checks for the highest-numbered RED image in the current
output directory, and set FRAMENO keyword to 1 above that value.
Usage
nextframer [n]
Arguments
n = value for next image's index number (FRAMENO)
Output
none
Exit values
0 = normal completion
1 = wrong number of arguments
-1 = output directory not found or invalid frameno
Example
1) Set next frame number to 123
nextframer 123
2) Set next frame number to 1 above the last frame number
nextframer