(Makefile): Updated comments about using LaTeX2HTML for the library

(Makefile):  Updated comments about using LaTeX2HTML for the library
	reference.  Made the extension to the input files for makeindex
	explicit; if not made explicit a directory of the given base
	name can cause makeindex to blow up.  Specifically, if there is
	a directory ./lib/ created by LaTeX2HTML, "makeindex lib" will
	fail, but "makeindex lib.idx" will not.

	l2h{tut,ext,lib} are now dependent on myformat.perl.

	l2h adds ls2lib and removes the non-existant l2href.