Fix year handling when converting HYDE population data to nc
Fix year handling when converting HYDE population data to nc

Define the time dimension as bounded so it can store the years.  Then
when storing (or reading) data use the index of the year we want.

ricardog/raster-project,ricardog/raster-project,ricardog/raster-project,ricardog/raster-project,ricardog/raster-project