revamp text rendering classes * base-text-renderer.h: New file. * ft-text-renderer.h, ft-text-renderer.cc: New files for freetype text rendering classes, adapted from txt-eng-ft.h and txt-eng.cc. * text-renderer.h, text-renderer.cc: New files. Public interface for text rendering. * gl-select.cc, gl-render.cc, gl-render.h, gl2ps-print.cc, graphics.cc, graphics.in.h: Adapt to use new text rendering interface that does not require checking HAVE_FREETYPE. * libinterp/corefcn/module.mk: Update.

gnulib-hg = gnulib-hg