Declare arguments const in the various structure accessors, so XCBGetSetup is not so painful to use.

 and add more button, key, and graphics enumerations.

for mask enumerations such as CW flags.
Replaces the C-specific use of 1<<n in xproto.xml

Portability fixes. Should help DragonFly and Solaris, and should not hurt anything else. Tested only on linux so far though.

API/ABI change: XCBSendRequest returns the sequence number instead of using an out-parameter. Now 0 is a special sequence number indicating failure.

Tweak to previous API change: Require that spare iovecs fall before vector[0]. Leave vector in well-defined state.

Use XPath position() function instead of xsl:number, to evaluate array indices while generating code for easier readability.

API/ABI change: XCBSendRequest callers must pad to 4-byte boundaries now. When not in RAW mode, a null pointer for iov_base is replaced by up to 3 padding bytes.

There's no more race condition between event and reply handling.
The *RequestBlind and *RequestChecked functions are not yet implemented.