timeout option, improved per-OS video specification

• added -t --timeout options, to allow specifying a finite time in seconds after which the stream will end. This can be helpful for remote installations where a cellular modem is used, and you want a sane limit on how much bandwidth will be used if you only need to monitor for a fixed time length

• improved ability to specify video streaming parameters in stream.ini, tested more thoroughly on real hardware (laptops) for Mac and Windows along with Linux to verify performance

• BUGFIX: corrected logic for missing .ini file, by a typo it didn't actually fail with a useful error when the specified or default .ini file was not found.

• improved test meaningfulness by using the same default stream.ini, to help avoid tests that missed bad default settings