fix flickering music OSD
Added optional parameter 'useCached' to xbmc.playSFX()
Added parameter 'useCached' to g_audioManager.PlayPythonSound(), default = true
When useCached is false, PlayPythonSound now frees any matching cached sound before continuing
Merge pull request #4555 from FernetMenta/musicosd

fix flickering music OSD
Merge pull request #4491 from ruuk/ignorecache

Added optional parameter 'ignoreCache' to xbmc.playSFX()