Changes since 0.1:

o rateplot: The option "grid" was not working, a grid was produced
            anyway. (10/5)

o ncut: Rd file clarified. (11/5)

o stat.table: - The "weighted.mean()" function now works correctly for 
                calculating standardized rates.

o Datasets added: thoro, mortDK, gmortDK, blcaIT, lungDK, births, S.typh.

Changes since 0.2:

o Option Exp added to ci.lin, allowing on-the-fly computation of
  exp( estimate, c.i. ).

o Structure of the dataset ewrates has been changed from three
  matrices to a single dataframe.

o stat.table: - count() now allows an id argument to count persons
              - Rd file expanded with nickel example.

o diet data: - person-years, y, has been added as variable. 
             - dates have bben converted to class Date.

o rateplot: 0 rates are converted to NA before plotting to prevent
            warnings from the log-axis.

o The cal.yr class and related function have been removed.

o The cal.yr function now returns an unclassed numerical vector.
  Accepts all sorts of date/time classes as well as character vectors
  and factors as input.