* src/ssconvert.c (setup_range): Parse in the context of the first
sheet.

* src/parse-util.c (cellref_as_string): Simplify and fix: let
gnm_cellpos_init_cellref do the work.

* src/position.c (gnm_cellref_make_abs): Simplify and fix: Let
gnm_cellpos_init_cellref do the work.