Animated zoom and scaled tiles implemented

[Jiří Techet <techet gmail com>]

Hi,

this has been a really calm release cycle. First because I didn't have
much time to implement new features and second that there have been no
bugs reported. No bugs reported can have two explanations: either
there are really no bugs in libchamplain or nobody is using it. I'll
assume the first option is right :-).

Anyway, I've just pushed a new feature which is animated zoom in and
out. This means that when you zoom in, you'll see the map scaled to
the new zoom level. The rescaled image stays in the background until
the new tiles are downloaded so it eliminates the blank screen moments
between two zooms. Basically it works similarly to Google maps. Please
test it and let me know if the animations should be adjusted in some
way. I'll also add some knob to make the animations optional.

I plan to make the first 0.12 release the next weekend. There won't be
any other major features in the 0.12 release - just some cleanups and
documentation updates (this time I should really find some time to
write a libchamplain overview and tutorial).

Cheers,

Jiri