Replace libeb with libebu which is actively maintained.

[nonwill]

libebu is available at http://green.ribbon.to/~ikazuhiro/dic/ebu.html

[mvf]

Finally looked into libebu, and I'm afraid the benefits are not worth breaking libeb source compatibility over. In particular:

libebu is not maintained enough:

• No version control
• No Windows support
• Not packaged anywhere

The new features, while nice to have, are not immediately useful for qolibri:

• AFAIK there are no UTF-8 dictionaries
• 広辞苑 Munsell color rendering is not implemented

All in all, it's not worth the considerable extra effort, both for qolibri and for downstream maintainers.