DVDSubtitleStream: better detect stream encoding and optimization
Use BOM detection for all supported charsets, not only UTF-8 and UTF-16LE
Do not double convert subtitle->wstring->UTF-8. Use direct conversion subtitle->UTF-8
additionally: CharsetConverter: subtitleCharsetToW -> subtitleCharsetToUtf8
[spectrum] cosmetic: Use static where appropriate
[rbp] Remove PiAudio engine
[rbp] Add PiAudio sink
[spectrum] Draw spectrum as a single object

glDrawElements is called 256 times per frame, once for each bar. It is more efficient to batch up larger blocks.
This change draws the specrum with a single glDrawElements call.

Looking at visualisation in full screen mode, it used to top out at 75 fps. With this PR it can hit 125 fps.
Support uClibc compilation

partly based on aports from Alpine Linux:
http://code.ohloh.net/file?fid=Up3lAbVglPtyupfNPazFHQYMKM8&cid=Sr-nRbkkE8E&s=&fp=302485&mp=&projSelected=true#L0
[epg] handle <onback> just like every other control
[pvr] no need to handle ACTION_NAV_BACK and ACTION_PREVIOUS_MENU in GUIWindowPVRCommon - they're handled in GUIMediaWindow already
[pvr] only handle ACTION_NAV_BACK in GUIWindowPVRRecordings if there's a parent directory to go to, else drop down to the base class as the action will be handled by the window system
Merge pull request #3920 from bkuhls/uclibc

Support uClibc compilation
fixed: Handle (non) URL encoding and forward backward slashes properly for path substitution
fixed: Copying of file(names) from non-URL to URL encoded filesystem
changed: Extend path substitude unit test
videodb: cosmetic in SQL query
CVideoInfoTag/CMusicInfoTag: make sure not to overwrite sortable fields with empty values (fixes #13850)
videodb: never use cached lookups during database cleaning
videodb: fix database cleaning for file-level sources
[WIN32] git clean directories as well but keep our downloaded depends
Merge pull request #3924 from popcornmix/single_spectrum

[spectrum] Draw spectrum as a single object
[rbp] Allow paplayer to be enabled on Pi