text-rendering

We can allocate those two in one vector allocation for all upon first non-nullptr setter. That would shrink hb_font_funcs_t by over 50%. Saves 33 pointers!

Edit src/pfft.pod, which is in perlpod format. Add any of the following (can be in separate PRs):

• --template
  • An overview of the template format and keys
• An overview or reference to Pango markup

Edit For bonus points, make it possible to autogen one of the manpage or the GLib arg