Last night and tonight's work...:

1) Use static deleters for singletons

2) Use new KUrl for KDevDocumentRangeObject when working with non-smart cursors. I found that even a blank KUrl (QUrl) allocates a QUrlPrivate, and this was hurting us - 5Mb memory use on a 1Mb document. Found on
profiling with Massif.

3) Locking for the definition-use chain.
- One top-level lock per chain for most functions
- Per-object locking (internally) for external references - not finished
- Use locking in client code

I have left debugging enabled for now... if you hit an assert, please
email/irc me.

4) Disable the duchainviewer. For this to work, there is still a fair
bit of work to be done:
- need notification of major changes to a duchain while unlocked
- need to create a proxy model which can forward data from any thread to the gui thread