New USB charging system, part 1 - API rework and user-visible setting update
1) "Charge during USB connection" option is now tristate: off/on/force. Currently "force" behaves just like "on", but in future it will allow charging even when it was not possible to positively identify a charger.
2) The H300 code has been adjusted to use the new system but there should be no functional differences, it already had the USB charging option and its USB/charging support is hardware controlled.
3) The Gigabeat S code has been adjusted to use the new system: the player now has the USB charging option, which wasn't previously available. The player will only charge at full speed when allowed to do so by a working USB host, so USB AC adapters won't work very well; however, they didn't work before either, so this is not a change in functionality.
4) The iPod Nano 2G code has been adjusted to use the new system: it already had the USB charging option. Using a USB AC adapter won't charge at full speed any more (it did before) - the old implementation was equivalent to the not-yet-implemented "force" option in the new system.
No other target should be affected. Support for the "force" mode and support for at least some other iPod models will come in a future commit :)
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26570 a1c6a512-1295-4272-9138-f99709370657