Merge pull request #74 from thebigspoon/master

fix for VRT OGR python example request issue #65
Merge pull request #76 from thebigspoon/clipraster

fix for issue #67, show how to clip raster with shapefile
Added recipe to convert an OGR File to a Raster
Merge pull request #77 from ustroetz/master

Added recipe to convert an OGR File to a Raster
Change project a geometry to project a layer because that is what it really does.  Fixes issue #69
fix for issue #78, break out vector and raster layer examples explicitly