Linearization feature

Add switch --linearize-ewkt, if enabled all EWKT geometries (yes, that means that it can be used only together with --convert-to-ewkt) are linearized before storing in database.
Internal linearization algorithm has several advantages over the postgis one (ST_CurveToLine):
  - Produces the same linearized form of curved segment regardless of its orientation
  - You cannot pass linear geometries to ST_CurveToLine, internal algorithm can handle this.
  - The number of interpolation points is calculated from the interpolation precision (fixed number in projection units), rather than from magical segment_count.