Overhaul isosurface.m and associated functions. * isosurface.m: Rewrite docstring and examples. Don't validate nargout. Wrap long lines to < 80 characters. Use names from docstring in code. Use "EdgeColor", "none" for Matlab compatibility, but preserve exception for gnuplot. Use blank lines between case statements for readability. Update demo #2 to properly show annotation textbox. Rewrite %!error tests. * __calc_isovalue_from_data__.m: Give private function a docstring. Use '_' in numbers as thousands separator for readability. Wrap long lines to < 80 characters. * __unite_shared_vertices__.m: Reformat docstring. Use rows() rather than size (XXX, 1). Wrap long lines to < 80 characters. Use space after function name and before parenthesis.

gnulib = http://hg.octave.org/gnulib