"Vier": New font version, fallback for oembed, more tracking variables removed

This pull request contains some changes to "vier". There is now a new font version that contains even more fonts that can be used in the future. The "reply" button is now a "reply" button that should be recognized as one.

Additionally the comment area is now hidden until "reply" is hit or if there is one or more replies to a post. This is more compact (The behaviour is inspired from GNU Social)

**Attention**: There seems to be a caching issue with Firefox and "Font Awesome". I had to do several reloads after changing the font to see all changes.

Besides these changes there are some minor changes as well:
* Sometimes the external oembed function doesn't work. I wrote a small replacement for this case (has to be extended in the future)
* Some more tracking variables are removed (in this case from Facebook)
* The conversion from HTML to BBCode now detects shared videos as well. (Useful for reimporting posts from pump.io that came from friendica)
* There was already a ".htpreconfig.php" file that is used to define the hostname. This file is now used at another place where the hostname is detected as well.