[Feature] playback logging from core

people don't like having to remember to run the TSR plugin so
lets meet them halfway

all tracks are added with timestamp, elapsed, length, trackname

added buffering for ATA devices

still needed:
-Done -- a plugin that parses for duplicates and reads the track info
to create the actual scrobbler log
(log can be truncated once dumped)
this should allow you to run the plugin at leisure

later I'd like to expand this logging to allow
track culling based on skipped songs..

remove the TSR plugin as hard disk no longer need to use it

Change-Id: Ib0b74b4c868fecb3e4941a8f4b9de7bd8728fe3e

manual/configure_rockbox/playback_options.tex

@@ -325,3 +325,15 @@ you to configure settings related to audio playback.
     \setting{Prefer Image File}. The default behavior is to
     \setting{Prefer Embedded} album art.
 }
+
+\section{Logging}\index{Logging}
+  This option will record information about tracks played on the device
+  in the following format 'timestamp:elapsed(ms):length(ms):path'
+  Devices without a Real Time Clock will use current system tick.
+  Tracks played for a very short duration < 1 second will not be recorded
+  to minimize disk access while skipping quickly through songs.
+  You should periodically delete this log as excessive file sizes may cause
+  decreased device performace see \setting{LastFm Scrobbler} plugin.
+\begin{verbatim}
+  the log can be found under '/.rockbox/playback.log'
+\end{verbatim}