ImageDiff: fix memory leak

Apparently, a BApplication eeds to be running for BBitmap or translation
kit stuff to properly free memory. Move the actual work to a separate
thread so we can keep polling stdin.
Fix build with animations enabled.

This is still not working, but at least it compiles.
More Haiku support in webkitperl and webkitpy

* Enable some extra features to in FeatureList to match other ports
* Add the --haiku option just like there is --efl and --gtk
* Get crash logs from Debugger instead of expecting Linux core dumps
Add installation instructions for the AHEM font.