;+
; NAME:
;  arradd
; PURPOSE: (one line)
;  add an array onto another.
; DESCRIPTION:
;  Append one array onto a source array.  If the source is
;  empty, return the appended array
; CATEGORY:
;  Util
; CALLING SEQUENCE:
;  new = arradd(source, append)
; INPUTS:
;	SOURCE	= Array to be appended to.
;	APPEND	= Array to append to SOURCE.
; OUTPUTS:
; 	NEW - New array with APPEND appended to SOURCE
; PROCEDURE:
; 	Could call boost_array, but instead we're
;	keeping this simple until something more
;	complex is needed. See code.
; MODIFICATION HISTORY:
;  2009 July 8 Leslie Young SwRI
;  2009 Sep 9  LAY added addrow keyword
;-

function arradd, source, append, addrow = addrow

    if n_elements(source) eq 0 then return, append

    if keyword_set (addrow) then begin
       return, [ [source], [append] ]
    endif else begin
       return, [source, append]
    endelse
end