Improve TimePicker

[Eugene Lazutkin]

TimePicker? should have following features:

1. It should be able to use 12-hour and 24-hour selection for hours.
2. It should be able to select minutes with 1-minute interval.
   1. Currently it uses 5-minute units to select minutes. It is impossible to select any non-divisible by 5 minutes (e.g., 53).
   2. In some cases user should be able to specify steps directly, or select from predefined steps like so: 1, 5, 10, 15, 30 minutes.
   3. In order to make the selector of minutes compact, it makes sense to use a slider widget.
3. In some cases user wants to specified seconds. In this case, a selector of seconds should be present.
   1. The selector of seconds may use steps just like the selector of minutes.
   2. The slider widget can be used just like in the selector of minutes.

Alternative way to make the time selector compact, is to make it similar to the clock widget (dojo.gfx-based). It may make sense to support a traditional and graphical time pickers.

Additionally see #1872.

[Adam Peller]

Consolidating under #599