[Sources.List] pageUp() and pageDown() don't page up and down

[prl]

[Sources.List]

The methods pageUp() and pageDown() move up and down in the list by 10 lines, independent of the visible page length, rather than actually moving by a full page.

They need to be implemented by deferring to Renderer.Listbox.move() which can correctly implement paging.

The methods selectNext() and selectPrevious() can be considerably simplified by also deferring to Renderer.Listbox.move().

[Peter Urbanec]

Fix Bug #576: [Sources.List] pageUp() and pageDown() don't page up and down

[Converter.StringList]

Implement a move() method that defers to self.master.move() (normally to Renderer.Listbox.move()).

[Sources.List]

Disable activation of wraparound through the class initialiser, leaving it to the skin.

Issue a warning if the enableWraparound argument to init() is not None.

Set self.enableWraparound to None for some sort of backwards compatibility.

Add method move() that defers to self.master.move() and eventually calls a method like Renderer.Listbox.move(), which handles wraparound via the Renderer's widget instance.

Implement methods selectNext(), selectPrevious(), pageUp() and pageDown() using move().

→ <<cset 2e05b54bb823>>