Add a test the confirms verify truncates the file as necessary.
Generalize the check for verify's error message.
There was a salvage test that (according to the comment) was testing
that a salvage operation with an open connection/session handle would
fail; the test is wrong, an open connection/session handle is fine, it's
an open cursor that will cause verify/salvage to fail, and the test
didn't actually test for a raised exception anyway.  Remove the test
from test_salvage.py, add test_bug006.py that confirms that verify and
salvage both fail if there's an open cursor.
Add the rest of the session methods that should fail with a cursor open.
Add mmap support for read-only objects (a read-only object is an object
using a checkpoint other than the "live" system).  Basically, when a
read-only object reads pages from the backing file, it maps them into
memory rather than copying them into the buffers.

This change adds support for a new class of WT_ITEM buffer, one that has
WT_ITEM_MAPPED set.  The WT_ITEM_MAPPED flag gets set when the buffer's
object is mapped into memory by the underlying block manager read call.

Add configuration string "mmap", defaults to on, turns off mmap calls.