Bump xcb dep to 0.8, bump xcb-util version to 0.2.

[mjkillough]

As some types (at least xcb::Connection and xcb::GenericError) are used in the public API of xcb-util, this is a breaking change for xcb-util too.

[meh]

Do you know what changes happened between 0.7 and 0.8?

There may be other changes required.

[mjkillough]

Apologies for the delay.

The CHANGELOG and diff between the most recent 0.7.x release and 0.8.0 are here: https://github.com/rtbo/rust-xcb/compare/0520c2fcd27636bb66f69bc4e069709f6f243f73...master

Notable changes are:

• Implementing Error for some error types
• Making cast_event/cast_error unsafe, as they're really just using transmute
• Some changes to xcb::connect

The first two would result in compile errors if code needed updating, but xcb-util compiles fine with the new xcb. The third change doesn't seem to affect xcb-util, as it never calls xcb::connect itself.

I've tried xcb and xcb-util with this change in one of my projects (mjkillough/cnx) and it compiled and ran fine.

[mjkillough]

Thanks a lot!