add set_struct_in_map

Signed-off-by: Mark Histed <mhisted@gmail.com>
frm_findrownum: completely reorganize the matching algorithm to deal with empty,nan,numeric,str,and cell for both match value and frm vector

Signed-off-by: Mark Histed <mhisted@gmail.com>
frm2xls: fix nit; insert spaces in column header names before numbers as well as capitals

Signed-off-by: Mark Histed <mhisted@gmail.com>
xls2frm: in text columns, make sure all empties are '' and not []

Signed-off-by: Mark Histed <mhisted@gmail.com>