Data can only be appended.

Add a test case for one.

Add inline test cases.
Fix several bugs brought up by test cases.
Alter PersistentString instances when they already exist rather than
creating new ones.

LOBTree raises when a key is out of range.

Credit to Vincent Pelletier.

In some cases, listing files is disallowed. Allow caller to disable
paramiko's default-enabled file size check to support these cases.

Drop parameters which are passed with default value.

Requires creating socket outside of paramiko.Transport .

In normal Zope usage, ZPublisher does this. TimerServer does not provide
publisher with a request (which would be irrelevant anyway), so
CMFActivity-managed transactions notes are empty.
Notes are useful to identify the cause of an object modification, so set
them in CMFActivity.