Revert "[sextante] removed "lib" prefix in saga calls"

This reverts commit 1c2e49ed249a89480c1195f50c96614dc72700d3.

Conflicts:
	python/plugins/sextante/saga/SagaAlgorithm.py
[sextante] adapted SAGA binding to support different versions in windows and linux
[sextnate] minor algorithm improvements and renaming
Changed how postexecution errors are handled in algorithms caling external apps

Improved R error messages