enable "segmentize"-like accuracy of polygon borders

[bbauerma]

during topological operations (overlap, intersect, etc) it is in general necessary to "segmentise" polygons, i.e. increasing the density of points that define the outline of the polygon.

For example:

1. A square in some local projection is defined by 4 points. In the local projection, this points are correctly connected by straigth lines.
2. When this square is warped to another projection, only the 4 points are projected -- the lines between the points will be drawn again just as straigt lines -- although the should be curved to represent the area and extent of the polygon correctly.
3. this troubles then the correct execution of topological operations

the remedy for this is to "densify" or "segmentise" the lines by adding additional points along the lines in 1) (libraries can do this already), and project all the points. These are then connected in a new projection with (wrong) straight lines, but as they are much shorter, the error is much less crucial

question is: how to control the correct segmentation length? user defined? related to the pixel raster size of a RasterGeometry()?