Initial commit for the Sony NWZ linux port

SUPPORTED SERIES:
- NWZ-E450
- NWZ-E460
- NWZ-E470
- NWZ-E580
- NWZ-A10

NOTES:
- bootloader makefile convert an extra font to be installed alongside the bootloader
  since sysfont is way too small
- the toolsicon bitmap comes from the Oxygen iconset
- touchscreen driver is untested

TODO:
- implement audio routing driver (pcm is handled by pcm-alsa)
- fix playback: it crashes on illegal instruction in DEBUG builds
- find out why the browser starts at / instead of /contents
- implement radio support
- implement return to OF for usb handling
- calibrate battery curve (NB: of can report a battery level on a 0-5 scale but
  probabl don't want to use that ?)
- implement simulator build (we need a nice image of the player)
- figure out if we can detect jack removal

POTENTIAL TODOS:
- try to build a usb serial gadget and gdbserver

Change-Id: Ic77d71e0651355d47cc4e423a40fb64a60c69a80

firmware/panic.c

@@ -115,7 +115,7 @@ void panicf( const char *fmt, ...)
     }
 
 #if defined(CPU_ARM)
-    backtrace(pc, sp, &y);
+    rb_backtrace(pc, sp, &y);
 #endif
 #ifdef ROCKBOX_HAS_LOGF
     logf_panic_dump(&y);