* For some reason, the polling methid is much more inefficient than I thought. According to htop it caused up to 15% CPU load on some phones (e.g. Galaxy S).
The event based causes no CPU load.
Rockbox' idle CPU load is now back to 0%, while it was previously dominated by polling the call state.
* Also stop on outgoing calls (no need to explicitely pause for making a call anymore).
* Factor out the detection mechanism to separate files.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28564 a1c6a512-1295-4272-9138-f99709370657
