Changes in snowfall 1.84
===========================
 o Bugfix sfExport: if exporting a NULL value, no error is raised.

Changes in snowfall 1.83
===========================
 o sfIsRunning: new function giving a logical is sfInit() was called or
   not. Needed, as all other snowfall functions implicitely call sfInit()
   if it was not called.

Changes in snowfall 1.82
===========================
 o Internal refactorings.

Changes in snowfall 1.81
===========================
 o Change in sfInit() MPI startup so sfCluster can run with
   snow > 0.3 now.
 o sfExport now also works in sequential mode (writing to
   global environment). This prevented sequential execution
   in some cases.

Changes in snowfall 1.80
===========================
 o snowfall passes packages checks of R 2.10.1 without warning
   or error. Internal state is now only saved in the namespace
   itself (thanks to Uwe Ligges for the tipp).
 o sfExport can now also export objects in a specific namespace
   (argument 'namespace')
 o sfExport: behavior in error case manageable (stopOnError)
 o sfExport: smaller bugfixes.
 o sfRemoveAll can now also remove hidden names (argument 'hidden')
 o sfRemoveAll is more robust now (some minor bugfixes, more checks)
 o sfRemoveAll bugfix for multiple removals (thanks to Greggory Jefferis)
 o Bugfix on exception list on sfExportAll
 o Refactorings in sfTest()
 o snowfall now has a NEWS doc ;)
 o No warning on Mac OS because of default Mac-R command line arg 'gui'
   (thanks to Michael Siegel).
