mac-syphon: Add "Allow Transparency" property

Transparency is now disabled by default, so that alpha values from
injected back buffers don't propagate to OBS (e.g. Minecraft doesn't
render properly in OBS unless "Allow Transparency" is disabled)
Remove ingest server live-ord.twitch.tv from services.json

Server doesn't exist anymore
https://api.twitch.tv/kraken/ingests
http://blog.twitch.tv/2014/09/service-update-chicago-point-of-presence-closure/
Merge pull request #289 from Gol-D-Ace/remove-twitch-ingest-server

Remove ingest server live-ord.twitch.tv from services.json
linux-v4l2: Fix select in capture thread.

This moves the enabling/resetting of the file descriptors inside the
capture loop so it is done before each select call. Why this even worked
before is unclear, but doing it the *right* way seems to reduce latency.
linux-v4l2: Make timestamp offset local.

This replaces the var in the source struct that are handling the
timestamp offset with a local one in the capture thread.
This change is mostly to make the code more readable.
linux-v4l2: Make frame counter local.

This replaces the var in the source struct that was used to print out
the number of captured frames with a local one.
linux-v4l2: Always display currently selected device.

This adds some code to the device enumeration that checks if the
currently selected device is present. In case it is not it will
add the device but disable it.
linux-v4l2: Disable properties when device is not there.

This adds helper function to disable/enable all properties which is
used in the device selected callback to enable/disable the properties
when the selected device is available/unavailable.
linux-v4l2: Update properties when devices change.

This causes the properties for v4l2 sources to be refreshed when a
device is disconnected/connected.
linux-v4l2: Avoid nested device open/close.

This moves the calls to the property modified functions so the old
handler can close the device. Otherwise this would cause the device
to be opened multiple times.