changed the R command behavior .libPaths() in RAlgorithm.py to add a .lib.loc and not substitute one
modifies the Advanced_Raster_histogramm.rsx in order to fully benefit from raster package RAM savety
Merge pull request #440 from MatMatt/master

[sextante] changed R command .libPaths to add and not substitute paths
[sextante]modified problematic headers
[sextante] deleted problematic help files
[sextante] fix typo
[sextante] fixed wrong import
Fix placement of simple markers in cached images
Reject features with empty geometry in QgsMapToolAddFeature