[libamplayer] Add HEVC format to Android 4.4 patch
[AMLUtils] Change some more permissions

In current Android 4.4.2 sources we need to change
permissions to 666 for following:

    /dev/amvideo
    /dev/amstream_sub
    /dev/amstream_sub_read
    /dev/amstream_rm
    /dev/amstream_mpps
    /dev/amstream_mpts
    /dev/amstream_abuf
    /dev/amstream_vbuf
[omxplayer] Remove PCMRemap and handle multichannel mixing like ActiveAE

omxplayer uses pre-ActiveAE code for determining multichannel mixing.
Some of the decisions made with lfe and side/back channels are different.

I think it is better to match latest xbmc code exactly, and so use
ffmpeg to determine the mixing matrix in the same way as Pi Sink does.
[utils] drop ASM from MathUtils::truncate_int() - standard cast to integer does what we want anyway.
[uriutils] add std::string version of IsInternetStream
[fileitem] adds Get/SetURL() to CFileItem to return/set a CURL of the path, and CURL based constructors.
[CURL] make the CStdString constructor explicit, to ensure we capture function conversion to CURL
[stdstring] convert some filesystem based functions to std::string
[uriutils] add CURL versions of various URI processing functions or helpers
[uriutils] rewrite CreateArchivePath() to return a CURL
[filesystem] split the filtering of hidden files from non-allowed files so they can be optimised
[filesystem] adds IDirectory::AllowAll() to take over from IDirectory::IsAllowed to save CURL processing
[filesystem] convert IDirectory interface to use CURL
[filesystem] adds CURL versions of CDirectory and CFile functions.
[filesystem] switch directory factory Create() calls to CURL
[cosmetic] minor cleanup in CDirectoryFactory::Create
[cosmetic] drop unused ZipManager::Cleanup function
[smartplaylist] use CURL for reading from files
[filesystem] cleanup CFileDirectoryFactory to use the CURL we pass into it where possible
[cosmetic] rename CFile::Cache to CFile::Copy as that's what it does