Support flicking borderless content like Maps using Flickable

Flicking dynamics should for the most part be the same for all content, when flicking an image, lists, web pages, maps, and so on. Flickable achieves this well, but lacks proper support for flicking borderless (or semi-infinite/very large) content like map models.

• Flickable contentWidth, contentHeight, contentX and contentY properties don't work well with borderless content
• new content can be loaded from the top, bottom, left and right edge of the visible area
• infinitely flickable lists can load content from the top, bottom, left and right edge of the list* possibly provide a separate Flickable element if the API changes don't make sense for existing use cases
• in many cases Flickable assumes it starts from the top-left corner of the content area - there is no such thing in Maps
• Flickable's current drag threshold handling sometimes causes blocky movement on touch screen devices

Pseudo-code example:

import Qt 4.7
import QtMobility.location 1.1

Flickable {
    id: flickableMap
    width: 300; height: 400
    contentWidth: Flickable.Infinite
    contentHeight: Flickable.Infinite
    onMoving: map.pan(delta.x, delta.y)
    children: [
        Map {
            id: map
            zoomLevel: 10
            plugin : Plugin { name: "nokia" }
            anchors.fill: parent
        }
    ]
}