0.24  2014-12-07

changes visible to the user:
- retropolation: 'td' will performs both extra- and retropolation if the high 
  frequency series covers a larger time span than the low frequency series.
- low frequency values are ignored if series is longer than high frequency 
  series (with a warning). 
- suggestion to use 'denton-cholette' when the original 'denton' method is 
  chosen.

0.23  2014-01-11

changes visible to the user:
- Our R-Journal article on temporal disaggregation explains tempdisagg in more
  detail. Links are included in the package description, the help files and 
  the README file.

minor changes:
- warning in ta() if a time series contains internal NAs.
- formating tweaks in the help files.


0.22  2013-08-07

changes visible to the user:
- predict method for 'td' is now different from fitted: 
  - $fitted.values of a 'td' object now containts the low-frequency fitted 
    values of a  regression or the low-frequency indicator in case of the 
    Denton methods. The values are be accessed by fitted().
  - The final high frequency series is now stored in $values. As before, these 
    values are accessed by predict().
- Package overview (?tempdisagg)
- Demo (demo(tempdisagg))
- argument 'truncated.rho = 0' instead of 'no.neg = TRUE'. This allows for
  truncation values different from 0. Default behavior is the same as in 0.21.

bug fixes
- in 0.21, ta() produced an error if less than a low-frequency unit was 
  covered by high frequency data. Now it produces series containing only NA.
- If a singular data matrix is entered, there is a new warning.


0.21  2013-01-21

changes visible to the user:
- new methods available: "chow-lin-fixed" and "litterman-fixed". 
  Using the "fixed.rho" argument, an autoregressive parameter may be specified
  by the user.
- interface changes: "chow-lin-maxlog-ecotrim" and "chow-lin-maxlog-quilis"
  are defined as new methods. No need for the old 'vcov' argument anymore.
- new defaults: method = "chow-lin-maxlog", neg.rho = FALSE
  with positive values for rho only, the chow-lin-maxlog method generally 
  outperforms the other methods.
- all relevant arguments are directly entered to td()
- summary output: If neg.rho = FALSE and a negative rho is truncated to 0, and 
  indicator is shown in the summary output.
- non time-series mode: optionally, standard vectors can be used instead of
  time series. In this case, the frequency of low frequency variable is 1,
  while the fraction of the high frequency variable is specified by the 'to'
  argument
- updated help files

invisible changes:
- td() is rewritten and has a clear structure now.
- GLS Regressions are performed by the new CalcGLS() function, which uses 
  QR-decomposition instead of matrix-inversion. This is faster and 
  numerically stable. It resolves an issue wher large (or small) numbers have
  led to a 'system is computationally singular' error.

