1) fix so that missing blob tables don't prevent table from being
    dropped
2) decrease size of blob part if record length exceeds max length
3) add test case for table wo/ corresponding blob table
4) init scan counters when sending scan_tabreq


mysql-test/r/ndb_autodiscover.result:
  testcase for table wo/ corresponding blob tables
mysql-test/r/ndb_autodiscover2.result:
  testcase for table wo/ corresponding blob tables
mysql-test/t/ndb_autodiscover.test:
  testcase for table wo/ corresponding blob tables
mysql-test/t/ndb_autodiscover2.test:
  testcase for table wo/ corresponding blob tables
ndb/include/ndbapi/NdbDictionary.hpp:
  Add non-const get column
ndb/src/ndbapi/NdbDictionary.cpp:
  Add non-const get column
ndb/src/ndbapi/NdbDictionaryImpl.hpp:
  Allow "partially" getTable, which enables dropping of tables
     that fails to create blob tables
ndb/src/ndbapi/NdbScanOperation.cpp:
  Init counter when sending SCAN_TABREQ
sql/ha_ndbcluster.cc:
  Make sure that blob don't have to big part size