Improve "Integrating QML And C++" section

• Exposing C++ Types To QML
  • needs extensive review
  • This needs to renamed to "Registering C++ Types With The QML Type System"
  • Should link to the tutorial on writing extensions
  • Need to document qmlRegisterExtendedType() in our sources
  • Needs restructuring, e.g. maybe
    • C++ types as QML object types
      • introduce how a C++ type can be a QML object type without modification - just need to register it
    • Registering types
      • How to register a type and call qmlRegisterType()
      • How revisions and versions work
      • "Inheritance and Coercion" and "Extension objects"
    • Helper stuff for QML types defined in C++
      • QQmlParserStatus
      • QQmlListProperty
      • others?

The other three sections need extensive review.

Suggest renaming and reorganizing these last three sections to:

Data Conversion Between C++ and QML

• Data ownership semantics
• Built-in Data Types
  • Supported data types
  • JavaScript Arrays and Objects
  • Using Enumerations of a Custom Type
  • Using Enumeration Values as Signal and Method Parameters
  • Automatic Type Conversion from Strings
  • Data Returned From Instance Method Invocation
  • Sequence Types
    (move all content related to context properties and default/attached etc. properties and Q_PROPERTY discussion to the "Exposing C++ Objects and Functions to QML" page)

Exposing C++ Objects and Functions to QML

• Embedding C++ Data into QML with Context Properties
• Exposing Q_PROPERTY properties
  • Instance Property Access
  • Exposing Qt C++ Properties
  • Default Property
  • Grouped Properties
  • Attached Properties
  • Object and List Properties
  • Property Value Sources
• Exposing C++ Methods
• Exposing C++ Signals

Accessing QML Objects and Functions From C++

• QML Objects, QObject and QMetaObject
• Loading QML Objects
• Accessing QML properties
• Invoking QML Methods
• Receiving QML Signals

All of the sections relevant to using C++ models with QML views should be moved to the QtQuick docs.