Adds lwcurve_linearize function at liblwgeom level.
Turns lwgeom_stroke into a wrapper, keept it for backward compatibility.
Reduces allocations in linearization procedures.

Implements SYMMETRIC and RETAIN_ANGLE flags.
Implements MAX_DEVIATION, MAX_ANGLE and SEGS_PER_QUADRANT configs.

Includes unit and SQL tests.
Includes documentation.

Closes #2464 (maxError configuration is MAX_DEVIATION)
Closes #3772 (balanced output is SYMMETRIC and RETAIN_ANGLE flags)

Document the new ST_CurveToLine signature

git-svn-id: http://svn.osgeo.org/postgis/trunk@15430 b70326c6-7e19-0410-871a-916f4a2858ee