====== READTH Command ======

READTH,<THFile>,<Pair>,<Num>

Reads a time history file into a line object for plotting.   

  * THFile – Full path of the time history file to be read
  * Pair - option to read time history in 1 or 2 column format
    * 0 - read one column time history (ACS SASSI output format)
    * 1 - read two column time history with time/accel. pairs
  * Num – reference number for the line object