New 'clock present' WPS tag: The tag checks for the presence of the clock hardware...

New 'clock present' WPS tag: The tag checks for the presence of the clock hardware and can be used unconditionally (returning a 'c') or in a conditional. You can specify what to display if a target has the clock (the true case) and an alternative for targets without. This can be useful for e.g. the greyscale 160x128 WPSs or the Archos ones which work on players with and without the hardware. - Add the new tag to the WPS tag description in the manual. Change the headline to the less technical 'Time and Date' as per the discussion in IRC.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20961 a1c6a512-1295-4272-9138-f99709370657