doc: Update documentation around java_get, java_set. * NEWS: Don't include java_get, java_set in list of functions deprecated in 3.8. * java.txi: Add java_get, java_set to manual. Write documentation for using '.' operator to read/write fields of object. Add examples of using Java interface. * java_get.m, java_set.m: Change @deftypefn type to "Function File".

geometryimages.m voronoi triplot griddata convhull delaunay inpolygon
interpimages.m interpft interpn interpderiv1 interpderiv2
plotimages.m plot hist errorbar polar mesh plot3 extended
sparseimages.m gplot grid spmatrix spchol spcholperm
splineimages.m splinefit1 splinefit2 splinefit3 splinefit4 splinefit6