Support for Arabic

[Minoru]

(Reported by alejandrogallo on IRC.)

Newsbeuter version (copy from newsbeuter -v): 2.8, 2.9, d20cf49

Steps to reproduce the issue:

1. Add https://arabic.cnn.com/rss to urls file.

2. Open any article, copy the text to, say, Vim. With an appropriate font (I used Dejavu Sans Mono) you'll see that the characters that are connected in Vim aren't connected in Newsbeuter. Here's a screenshot by alejandrogallo:

Other info you think is relevant: Vim does it just fine, but it uses some complicated-looking code to achieve that; see src/arabic.c.

TODO:

• Look for a library that'll do everything for us
  • Check if NeoVim already uses such a library to replace src/arabic.c from original Vim