Log Message:
Update to 0.1.18.  Changes:
* Added --purge [<days-old>] option which lets you purge old completed items.
* Can now use force-colour in the todorc.
* Various patches from Debian and Gentoo maintainers applied. These fix
  compiler errors on recent GCC versions, uncaught exception when TERM is not
  set, a few man page issues, issues with the BASH scripts and miscellaneous
  other things.