Loads a colour table that defines the RGB values corresponding to 
  given colour indices (used when a plotting terminal is not set to
  the decomposed mode).
The first argument may be used to chose from one of the 41 predefined
  colour tables, see example below for a graphical list of the colour
  predefined tables.
\gdlcodeexample{loadct_0}{}{loadct}
\gdlkeyworddesc{GET-NAMES}
When set to a variable, a list of colour table names (string array) 
  is assigned to that variable.
\gdlcodeexample{loadct_1}{get_names}{}
