QMLObserver links against the library dynamically. User's apps can also
link to it statically, so that the app can be deployed with debugging
features to a device, without having to worry about library deployment.

All the expended item need to be retreived before we can call endCycle

Skip all signals and slot, there is too many of them,
and it is not usefull in the debugger.

QVariant does not work as they can contain custom type that corrypt the stream

Unfortunatelly, streaming QVariant is not a really good idea, as streaming
a custom type would fail

The agent is only attached when creator request it.  But this may occurs
After some scripts have been initialized. Which mean we do not get the
scriptLoad call.

The idea is to only enable it if it is run with -debugger, but for now
it is always enabled for simplicity.

This let you debug QML Javascript from creator