legend.m: Overhaul function for greater Matlab compatibility. * legend.m: Add '{' and '}' and cellstr calling form in docstring. Add additional calling form with PROPERTY/VALUE pairs to docstring. Reword documentation for greater clarity. Use texinfo features in multitable to structure explanation of "outside" parameter. Expand Implementation Note to discuss more of legend features. Remove cumbersome handling of __plotyy_axes__ property which now returns a matrix value, always. Add "first" to unique() call to fix labels being out of order on plotyy charts. Delete parsed options in varargin, because the remainder are now passed as PROP/VAL pairs to the legend object. Accept "none" as Location value. Change 0 input argument case to create a legend if it does not exist (equivalent to "show"). Replace sytax of for loops over number of elements of a matrix with a direct for loop over each element of the matrix for code clarity. Only create up to 20 data labels automatically, and issue a warning if there are more. Recode while loops to find objects to label as they would frequently fail with bad-index warnings when index was allowed to reach 0. During creation of a new legend, set fontsize to 90% of axes fontsize. Add property, "autoupdate", although it is unimplemented. Change default edgecolor to [0.15, 0.15, 0.15] to match Matlab. Don't inherit other font properties from axes. Get rid of unwind_protect block and always create text objects using "units" of "points". Change callbacks to have "cb_" prefix and to use more informative names. Add "zliminclude", "off" to properties of invisible text object so that it won't be included in any axes limit calculations. Update %!demo blocks. Add new BIST tests. * legend.m (cb_legend_update): Modify to handle plotyy axes without throwing an error. * legend.m (cb_legend_text_update): Use indexing, rather than for loop, for performance. * legend.m (cb_legend_hideshow): Change input variable names for clarity. Use foreach loop rather than for loop for clarity.Use indexing, rather than for loop, for performance. * legend.m (cb_legend_location): New subfunction callback for "location" property. If location is "none", rely on "position" property. Otherwise, rebuild legend in new specified location. * legend.m (cb_axes_deleted): Remove deletefcn from legend before deleting it to avoid unnecessary callback. * legend.m (cb_restore_axes): Rename variables for clarity. Check position to restore is not empty before restoring it. * legend.m (cb_line_listener): Use indexing rather than for loops for performance.