Added title, alt, iso of g elements.

__To Limit the Shapes Rendered (and improve loading performance)__
1. adds a smoothing parameter which says, combine points if they're less than _smoothing_ (makes shapes simpler)
2. adds a minPixelSize parameter which will not render polygons that are less than _minPixelSize_ in width and height (good for getting rid of small islands)
3. adds a minPolygonSides parameter which will not render polygons with less than _minPolygonSides_ (good for getting rid of points and vectors on a map)

__other (from mcordial)__
1. allows propagation of ids from parent <g> elements down
2. handles numeric widths and heights with units