[Feature] Persist pitch settings through reboots part deux

Revisit this after discussion with chris_s on IRC and forum

Pitch menu now changes icon when pitch has been changed

uses NVRAM to save the pitch settings unconditionally

Manual updated

Change-Id: Idcb4c2b7fe42f7a203dc4bfc46285657f370d0fd

lib/rbcodec/dsp/tdspeed.c

@@ -27,6 +27,9 @@
 #include "dsp-util.h"
 #include "dsp_proc_entry.h"
 #include "tdspeed.h"
+#ifdef ROCKBOX
+#include "settings.h"
+#endif
 
 #ifndef assert
 #define assert(cond)
@@ -402,6 +405,9 @@ void dsp_set_timestretch(int32_t percent)
 
     struct dsp_config *dsp = dsp_get_config(CODEC_IDX_AUDIO);
     dsp_configure(dsp, TIMESTRETCH_SET_FACTOR, percent);
+#ifdef ROCKBOX /* filter out invalid by grabbing the value actually set */
+    global_status.resume_speed = st->factor;
+#endif
 }
 
 /* Return the timestretch ratio */