Add new test file e_walauto.test.
Changes to threadtest3 so that "stress2" is more similar to the SDS stress test.
Make sure the sqlite3BtreeCount() routine does not leave index cursors in an
inconsistent state, as doing so might result in an assertion fault inside
of sqlite3BtreeKey() called from saveAllCursors() if content is deleted out
from under the statement that issued the sqlite3BtreeCount() call.
Enhanced "stress2" testing in the threadtest3.c test program.