Handling GenericEvents in XSendEvent()

[Carlos Garnacho]

Hi!

A few weeks ago I sent some patches to make XSendEvent() deal with
GenericEvents, which stayed mostly unreviewed, I'm reposting these,
rebased against recent masters, also including some docs for the XGE
updates.

Any comment is welcome, IMHO it'd be great to have this so a XI2-aware
implementation of XEmbed can be done sooner rather than later.

Cheers,
  Carlos