Move SRID handling into AbstractGeometry class.
Separate function for calculating arc center to to GeometryUtils class.
Conversion of circle to EWKT now uses the code of CircularString.
Rename classes to better reflect the data:
CircularString -> Curve
LineString -> Line
MultiCurve -> MultiLine
MultiSurface -> MultiPolygon
Merge pull request #15 from xificurk/GML-refactoring

GML refactoring