Use the IAnnotationModelExtension.modifyAnnotations method when possible

It turns out the IAnnotationModel connect/disconnect dance doesn't actually
do any batching of changes, so we now do that ourselves, using this
glorious method to update everything in a single operation
Switch PIDE editor annotations on by default

Now that the performance problems are gone, this is the right thing to do.
The option will, for now, be kept in as a safety measure
Bumped the version numbers to 0.4.6.6 and added a changelog entry