Add a --dtshd option

The spdif decoder was hardcoded to assume that the spdif output is
capable of accepting high (>1.5Mbps) bitrates. While this is true
for modern HDMI spdif interfaces, the original coax/toslink system
cannot deal with this and will fail to work.

This patch adds an option --dtshd which can be enabled if you use
a DTS-capable receiver behind a HDMI link.
manpage: fix --no-dts typo
Remove vo_fps global variable

This is needed by the encode stuff for some reason, so we have to
explicitly pass it. Functionality shouldn't change.
vo: Separate vo options from MPOpts

Separate the video output from the big MPOpts structure and also only pass
the new MPVOOpts to the vo backend.