[ios] - fix compilation
[settings] - don't hide passthrough settings on ios - visibility is now automagically determined by available audio device types
[ios] - add some pointer checks
[ios] - return optical device type for ios when external screen is used (makes the passthrough options visible when external screen via hdmi is attached)
[ios] - when device was not found - return false on initialize
[ios] - ensure to compare with the lower string device name (might be my test case only but i had a upper case device name in my guisettings.xml and sink wasn't found)
[ios] - decrease ringbuffer to 16384 bytes - gives low lag and behaves good in tests