Fixed bug related to sc_time showing SC_S instead of SC_SEC and a bug when...

Fixed bug related to sc_time showing SC_S instead of SC_SEC and a bug when using microseconds and invalid characters were generated in the syscams code. (syscams)
Fixed bug related to delays in input converter ports and current TDF time going negative. (syscams)
Fixed bug with Fraction conversion, using BigFraction instead of Fraction. (syscams)