keyboard: create after command line parsing

This avoids early exit due to e.g. file not found from messing with terminal settings
Add missing error.h include
Makefile: Add .PHONY for phony targets
ffmpeg: bump to 2.2.4
text: Remove unused subtitle code
Revert "Fix check for EOF"

This reverts commit 99c564db39831ca3f6b9b344f09277348f953b9c.
omxcore: Use const more