Fix Issue97 (-R option)

The gap is now calculated in trafgen.c based on the rate and the block size.
Therefore, during parsing, -R does not depend on -U anymore.
-R option: Removed unneccessary 'o' type specifier

'-R s=#o' is only substitute for '-G s=g,C,#'
Merge pull request #100 from erzb5e6f65/fix_Issue97

Fix issue97