Fix dc_roms_read_data.
Fix dc_roms_read_data.

If successive files had only one timestep but I wanted a 4D hyperslab,
then things didn't work. Work around this by doing the squeeze operation
only once everything has been read. This means that (start,count) have
dimensions of actual variable and I don't have to change values for
slices. Much simpler this way.

dcherian/tools,dcherian/tools,dcherian/tools,dcherian/tools,dcherian/tools,dcherian/tools,dcherian/tools,dcherian/tools