RaspiVid: Make open_filename() unified for all outputs (video, imv, pts)
RaspiVid: Make open_filename() unified for all outputs (video, imv, pts)

Add parameter filename to open_filename() so that it can be used for both
video, imv and pts outputs.

This removes the need for separate functions open_imv_filename() and
open_pts_filename() and allows the user to stream imv or pts to socket
as well.

Signed-off-by: Adam Heinrich <0e18f44c1fec03ec4083422cb58ba6a09ac4fb2a@adamh.cz>

maroviher/userland,6by9/userland,maroviher/userland,6by9/userland,adamheinrich/userland,raspberrypi/userland,gonzoua/userland,kraj/userland,6by9/userland,kraj/userland,raspberrypi/userland,gonzoua/userland,adamheinrich/userland,JamesH65/userland,raspberrypi/userland,JamesH65/userland,adamheinrich/userland,gonzoua/userland,kraj/userland,maroviher/userland,JamesH65/userland