Code review comment for lp:~zorba-coders/zorba/bug-1123165

- The fix for dynamic_function_invocation seems to be orthogonal. Why is this fixed in this merge proposal? I couldn't find a test to cover this behavior.

- The function check_xquery_feature_options is too long. Could this be simplified and/or split into multiple functions? It feels like most of the implementation should go into the translator and not into the static context.

- The style of the error messages is not consistent with the other error messages. They should be changed as follows:
  XQST0120 "$1": feature not supported
  XQST0128 "$1": unable to disable a supported feature
  XQST0126 impossible to activate all extension features