SplitView is very primitive

The QMLSplitView is very unintuitive to use. This is caused by the fact, that only the item, which has the SplitView.fillX boolean set to true is resizable. This has the problem, when having the "resizeable" view being shrinked to the minimum, other Splithandles can't be moved anymore.

Also having the resizable view being maxed out, will prevent other views to be shrunk, since the "resizable" widget is not capable to give more space.

My refactoring proposal is:

• Remove SplitView.fillHeight SplitView.fillWidth, since the direction is handled by the orientation
• Let resize ability depend on the preferred, minimum and maximum height / width.
• Introduce a shrinking and increasing policy for the hole Splitview: ResizeNeighborsFirst, ResizeNeighborsLast, ResizeUniformly, ResizeToPreferredFirst.

When not removing the SplitView.fillHeight SplitView.fillWidth; add at least another property named SplitView.shrinkHeight SplitView.shrinkWidth to implement an own policy.

Currently, a QML-SplitView is only usable with 2 children.