Silly style fixes
Fix Deskbar clock show/hide when Deskbar is hidden.

Bug #9469 happens because I set the showClock checkbox or not based on whether
or not the clock is currently hidden. This works most of the time, but if
Deskbar is hidden the clock is also considered to be hidden and that isn't what
I want in this case.

The solution is to override BView's Show(), Hide(), and IsHidden() methods
in TimeView to ignore whether or not the window is hidden when considering if
the clock is hidden.

The commit also deletes some no-longer-used private member variables of
TimeView.

Fixes #9469