Merge pull request #1 from takikawa/master

Fix "type" of XUngrabButton
Some reformatting, no fundamental change
some cleanup
fixing some XCreateGC, but xsnow.rkt still not working on my machine
updated XAllowEvents
add atom->number helpers
fix XSendEvent
add make-ClientMessageEvent
fixing X and make- ClientMessageEvent (again).

It now uses array for the data.
Maybe a union of arrays would be easier to deal with?
added function to convert a clientMessage-data to a vector.
+ added some check tests to avoid future problems (though it could be better tested certainly).
print with ~v instead of ~a in debug mode
Xinerama bindings
rename defx11 -> defxi in xinput.rkt
rename defx11 -> defxpm in x11-xpm.rkt
reformatting
Oops... renamed ' xinerama.rkt' -> 'xinerama.rt'
syntactic simplifications
fixing the XFree calls?
fix XListProperties
fix XGetWindowProperty and add helpers