Support more sequence types in QML

As per QTBUG-20826 we currently do not support sequence types in QML. This task is to determine what level of sequence support is possible in QML, and to implement it. A large amount of research and prototyping has already been done (see http://codereview.qt-project.org/#change,2838 and http://codereview.qt-project.org/#change,2903) but no code that is ready for integration into mainline exists.

Requirements:

1) Sequences of common stack types (at least int, qreal, bool) must be supported
2) Performance must be a primary consideration
3) Syntax must be consistent (ie, in QML, doing someObj.listProperty[3] = someValue; MUST update (write-back) the list in the someObj).
4) Allow assignment of single values to sequence types in QML (eg, string to stringlist property)

Steps:

1) Determine whether (and how) it would be possible to support value types in sequences properly (eg, being able to do someObj.vectorListProperty[3].x = someXValue; must work). If not, don't "half" support sequences of these types.
2) Polish prototype code into final state
3) Write unit tests
4) Write documentation

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Current status (30/09/2011):

Prototype code exists for various sequence types, including unit tests, however value-type support is still imperfect.

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Current status (05/10/2011):

Researching whether the solution can be simplified (at the moment the sequence-type specific wrapper classes are QObject-derived; if this is not required, we can use template classes to implement the wrappers, greatly reducing LOC required).

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Current status (17/10/2011):

Rewrote solution so that the wrapper classes are not QObject-derived, cleaned up the code, significantly expanded the unit tests. Code is currently awaiting review.