Make the safe areas respect the EBU R 95 and Rec. ITU-R BT.1848-1
standards for 16:9 content.
Links: https://tech.ebu.ch/docs/r/r095rev1_March2016.pdf and
https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1848-1-201510-I!!PDF-E.pdf

This ensures the pixel correctness of the sources selection highlight
boxes when on a fullscreen projector.

When on a windowed projector due to the nature of int<->float
conversions and also due to the limited space, some source boxes
might be like 'off-by-one' and barely noticeable.

When not in studio mode the preview and program sources are the same
but the checks will be made against GetCurrentSceneSource which were
resulting in the multiview source highlight to give the previewColor
where in this case we want the programColor.

The same effect is achieved by painting the whole canvas with
the outerColor

The Init function were only called on projector creation so this isn't
needed to be on a separate function. Its clearer to read the code.

This commit series changes the ini user configuration multiview layout
so that string values were converted to int. In order to prevent past
user saves to break we verify if the ini still have string values and
convert that to int on obs init.

This will make the code easier to maintain in clearer to read the
multiview layout settings, also, makes the addition of new layouts
easier.

Add Vertical Mixer Toggle

AppVeyor recently removed QT 5.7.1 for the Visual Studio 2015 image.

UI: Fix OBS_FRONTEND_EVENT_PREVIEW_SCENE_CHANGED

OBS_FRONTEND_EVENT_PREVIEW_SCENE_CHANGED is supposed to be called
whenever the user changes the current preview scene -- it was almost
never being triggered.

Makes it so the auto-updater does not have to rely on a cmake variable
being set.  Fixes a bug where deployment could accidentally be built
without the auto-updater being enabled.

UI: Fix memory leak when drag/dropping

XInput Support

Allows the ability to choose the number of chat lines when using the
"Chat log mode" feature.

Closes obsproject/obs-studio#1280

This enables extra mouse buttons to be detected by libobs. This allows
up to 29 extra buttons.

Ubuntu 17.04 updated libxcb1-dev to 1.12 where xinput should be enabled
by default but debian disables it by default atm. Compile libxcb with
--enable-xinput to use this within obs. Arch enables it by default,
debian does not and fedora is untested.

libobs: Expose source save/load signal

Adds an option to enable/disable blocking hotkeys when the window is in
focus which is normally used in order to prevent hotkey/shortcut
conflicts.  This does not apply to the settings window; the hotkey
behavior is unchanged with the settings window (in order to prevent
hotkeys from being used while setting hotkeys for example).

Closes obsproject/obs-studio#1267