18.10 RDSEED_MANY, chop up seed file

The program reads a large SEED volume and divides it up into several files of the same size. It calls rdseed, so rdseed must be installed. Rdseed can do the same, but RDSEED_MANY is simpler to use.
Example:

rdseed_many
Seed file name
test.seed
start time YYYY,MM,DD,HH,MM
2005 01 01 01 01
Interval in minutes
20
Number of intervals to extract
200

The output format is SAC, other format require a change of the program.