CreateCursor, valueMask and format

Hello !

Here is all I did to make this lib works as I expected.
There is more tests that pass here now :p

Feel free to comment, criticize and discuss !

Ps: Some format you gave for configureWindow were strange (like 'ssx' or 'Cxxx' , maybe a typo error ?)
Also, why do you add these 'xx' everywhere ? 
Yeah, here I'm iterating over all expected properties and if value not undefined add bitmask and value: https://github.com/sidorares/node-x11/blob/master/autogen/generate.js#L279 ( try to do `node generate` to see genarated result )