Cleaned models.py
Corrected smooth and offset properties in LineSymbolizer.mapnik().
Removed Gdal format parameter.
Hacked suppression of line offset in legend rendering.
Other cleaning...
Replaced deprecated mapnik Filter for Expression.
Simplified model properties serialization through model inheritance.
Simplified style import through inheritance.
Simplified model specialization.
Synchronized properties with mapnik2.2.0.
With exclusion of DataSources and ShieldSymbolizer.
Rewritten Text and Shield symbolizer to inherit common attributes.
Method get_xml moved to parent Symbolizer class.
Added image_size() method. Swapped symbol_size return value to (width,height).
Swapped size order to PIL-like (width, height).
Simplified Text and Shield Symbolizer mapnik() method.
Fixed image size setting for scaled images.
Removed extra Legend methods.
Layer and Style xPath more precise.
Regenerated style after models refactoring.
Fixed legend recreation.