Groups are no longer enum values but identified from snippet providers.

Since in the snippets overlay the selections are created with
ExpandBegin the interest is mostly in detecting when the first one
moved to the left (for example, when an undo is performed right
after inserting the snippet). However, this tracking doesn't need
to necessarily be associated with that flag.

- Restored removed built-in snippets.
- Revert a built-in snippet.
- Reset the snippets collection.

Reloading and synchronizing are now directly accessible from
the collection interface.

And mark the completion item as a snippet.

When editing one variable from a code snippet, all other variables
with the same name are updated accordingly.

Provide an interface so users can create/edit/remove snippets.

This avoids flickering, since parentChanged now
comes after property changed.

We select now after the drop event.
Some fixes for the out of process stuff.

Task-number: QTCREATORBUG-3242

Add USB protocol and chunking.

The mainFile property of QmlProject is the default file to run. People
have still the opportunity to override this in their run settings,
though.

The wizard generated code was updated accordingly. Note that this makes
projects generated by the wizard incompatible with QtCreator 2.1!

Task-number: QTCREATORBUG-3249

Reviewed-by: Erik Verbruggen

Conflicts:
	doc/qtcreator.qdoc
	src/plugins/qmldesigner/designercore/instances/nodeinstance.cpp
	src/plugins/qt4projectmanager/qmakestep.cpp
	src/plugins/qt4projectmanager/qt-maemo/maemopackagecreationstep.cpp
	src/plugins/qt4projectmanager/qtversionmanager.cpp

Task-number: QTCREATORBUG-3312

This is necessary to handle "live updates". Originally done by ck.

Task-number: QTCREATORBUG-3063

Splitted up patches wrongly

We check the qml file/document now with QmlJSCheck.
We explicitly disable checking of qml types.

We are checking for duplicate ids and duplicate property definitions now.

We have to check also for the ModelNode, but we also have to avoid
recursion.

Reviewed-by: Marco Bubke

Properly detach from rewriter view and node instance view
on model destruction.

Reviewed-by: Marco Bubke

Using the convienience class does not really save code and adds another
needless level in the hierarchy. This affects the three remaining BaseMode
users: Help, ProjectExplorer and HelloWorld.