Fix OffsetCurve to ensure end segments are included

[dr-jts]

This fixes the OffsetCurve algorithm to handle rare cases where an end segment is dropped because of heuristics used to reduce the number of short segments in generated buffer curves.

Example

LINESTRING (4.821 0.72, 7.767 1.801, 4.94 9.552, 0 7.79, 2.858 0, 4.821 0.72)

Offset curve Distance - -0.045; Mitre Join

Before:

Fixed code: