ndb/include/ndbapi/NdbScanOperation.hpp:
  Improved doc. a bit
ndb/src/ndbapi/NdbConnectionScan.cpp:
  Set error code
ndb/src/ndbapi/NdbScanOperation.cpp:
  Check error directly after taking mutex
ndb/test/ndbapi/testScan.cpp:
  new scan test with lots of threads
ndb/test/run-test/daily-basic-tests.txt:
  Added two more scan tests
  Collapsed testTransactions & testOperations