CODE: more work on mesh (vertex split); add test_mesh
CODE: change ASSERTX so formatters in assert message are ignored
DOCS: expand Rationale, Timeline and update Diary
CODE: more work on vertex split
CODE: mesh vertex split partially working
CODE: mesh vertex split changed to traverse clockwise
CODE: fix mesh vertex split for no split edges (begin == end)
DOCS: update Diary
CODE: remove debugging in mesh vertex split
CODE: fix mesh vertex split return value for corner-case
CODE: better messages and documentation