FOTS: option default ns not supported

[Sorin Marian Nasoi]

from:
http://www.w3.org/TR/xquery-30/#doc-xquery30-OptionDecl
"If the EQName of an option does not have a prefix, the expanded QName is in the http://www.w3.org/2011/xquery-options namespace."

The following queries fail in Zorba:

Query 1:
declare option require-feature "higher-order-function";
let $f := sum#1 return 0

result [err:XPST0081]: "require-feature": can not expand namespace prefix to URI

Query 2:
declare option require-feature "schema-validation";
1

result [err:XPST0081]: "require-feature": can not expand namespace prefix to URI