Missing/wrong keybindings in start-early/end-late widgets

[gigem]

The keybindings for the start-early widget in the new schedule editor are backwards. LEFT should move the start time earlier and RIGHT should move it later.

For both the start-early and end-late widgets (and probably anything else derived from the same base widget), the ability to move in big increments using PAGEUP and PAGEDOWN seems to have been lost.

[stuartm]

The keybindings are correct, what is backwards is the contents of the list, the spinbox widget currently works from negative (left) to positive values (right). The start/end offsets work contrary to logical behaviour, a negative start offset means a later start time etc. I'll have to work around this in the widget by allowing a reverse ordering.

I'll override PAGEUP/PAGEDOWN for spinboxes to offer similar/identical behaviour to the old widgets used in the Scheduled Editor. They currently move through the items a 'page' at a time, where a page is the number of visible items, since the spinboxes in current themes only show a single item it only moves by one.

[stuartm]

(In [21902]) Allow a spinbox to run from high to low when the supplied range calls for it. Refs #7073

[stuartm]

(In [21903]) Reverse the range arguments to the spinbox for start offset. Negative values for start offset cause a recording to start late and vice-versa, which is confusing. This change causes the spinbox to display them in the logical order. Refs #7073

[stuartm]

(In [22092]) Support paging by multiples of the step value in MythUISpinBox, defaults to multiples of 5 but the figure can be defined as an optional argument to SetRange?(). Requires a make clean. Fixes #7073