[rbp] Add streamsilence option for hdmi

This adds a (mostly) dummy audio engine for Pi which supports drain allowing the
stream silence gui option to appear.
The OnSettingsChange callback enables or disables the stream silence on the GPU.

Enabling this keeps the receiver awake, and avoids losing the first couple of
seconds of audio at start of playback.
Requires updated firmware.
Fix make check compilation.

TestRarFile: StringUtils::EndsWith no longer takes a third parameter
TestCharsetConverter: CCharsetConverter::subtilteCharsetToW's first
parameter cannot be a std::wstring, ::stringCharsetToUtf8 renamed to
::ToUtf8
TestJobManager: CJobManager::IsPaused renamed to IsProcessing with reverse
effect, s/UnPause/UnPauseJobs. Only PRIORITY_LOW_PAUSABLE jobs can be paused.

 There is a race condition upon calling IsProcessing for the first time
 after AddJob is called - the job may not have been started yet and not
 added to the processing list. As such, the test implements a custom CJob
 that allows the calling thread to block until the job has started processing
 such that IsProcessing can be checked in a deterministic way.

 CancelJobs effectively renders CJobManager useless after it is called,
 because m_running is set to false. A new member "Restart" was added to
 set this variable back to true when appropriate.

 IsProcessing should have returned false when jobs were paused.

TestSortUtils: SortItems is now a std::vector<boost::shared_ptr<SortItem>> not
an std::vector<SortItem>
TestStreamDetails: Aspect ratio 2.39 is now within the 2.37 - 2.47 range and
as such snaps to 2.40
Merge pull request #3376 from smspillaz/fix-tests-04102013

Fix make check compilation.
Merge pull request #3356 from popcornmix/streamsilence

[rbp] Add streamsilence option for hdmi