[Chandler-dev] FloatingTZ changed

[Andi Vajda]

I upgraded the build to PyICU 0.6-78. In that version FloatingTZ changed.
A floating tz, such as ICUtzinfo.floating, can now wrap a specific tzinfo 
instead of being hardwired to default to the default timezone.

As a consequence, FloatingTZ is no longer a subclass of ICUtzinfo.
It's a sibling of ICUtzinfo, and both are subclasses of datetime's tzinfo.

Andi..