Versopm 0.1.5

`MoveFront` can now move more than one variable to the front of a data frame.

Documentation improvements.

Version 0.1.4

Added `slide` and `shift` functions for lagging and leading variables. `shift` is largely based on TszKin Julian's `shift` function: <http://ctszkin.com/2012/03/11/generating-a-laglead-variables/>.


Version 0.1.3

Added `DropNA` to drop observations in a data frame with missing values for given variables.


Version 0.1.2

Stop message for `MoveFront` when variable does not exists. Other minor documentation changes.

Version 0.1.1 

Minor update to `FillIn` for data.frame 1.8.8.

Version 0.1

First version including the `FillIn` and `MoveFront` commands.