Gets an option in the options tree structure or return a default value.
# S3 method for Options
getOption(this, pathname=NULL, defaultValue=NULL, ...)Not used.
If a single option is queried, a single value is returned.
  If a vector of options are queried, a list of values are returned.
  For non-existing options, the default value is returned.
*hasOption().
  *setOption().
  For more information see Options.