Checkpointing: fixed a bug that prevented future checkpoints from being...

Checkpointing: fixed a bug that prevented future checkpoints from being created if a crash occurred during a checkpoint
DiskLogger: BabuDB can now recover from logs with negative log entry sizes
misc: prepared for release 0.3.2, added ChangeLog

git-svn-id: https://babudb.googlecode.com/svn/trunk@231 d4c7dd96-b7b2-11dd-893d-d98698f66bbf