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

When drawing cursor to window capture area - use actual resource width
and height instead of system metric values for icons.  Fixes an issue
where under rare circumstances, certain cursors would not draw at the
correct size.

Closes obsproject/obs-studio#1284

docs/sphinx: Fix typo in script sources section

Allows the ability to (optionally) synchronously create/update a
directshow device source rather than always asynchronously update the
device.  This is useful if creating/destroying scenes/sources very
quickly, and helps minimize the risk of creating new directshow sources
that use the same device, yet may not activate because an existing
source may already exist.  To use, set "synchronous_activate" to true in
its settings when updating or creating.  Note that this setting will be
erased after it's used, and will not be saved to user settings, so it
must be set each time in order to be used.

Closes obsproject/obs-studio#1228

Uses WaitConnection() when calling obs_frontend_set_current_scene to
ensure that the calling thread and the UI thread are synchronized when
setting the current scene via this function.

Closes obsproject/obs-studio#1234

Allows the ability to add a new scene collection via the frontend API.
Blocks until the scene collection has been successfully added to ensure
synchronization between the calling thread and the UI thread.

(Jim: Added detailed description to commit message)

Closes obsproject/obs-studio#1232

Instead of queuing AddScene to add the new scene to the list box,
ensures that the UI has added the new scene to the list box when the new
scene is added.  This ensures synchronization between the calling thread
and the UI thread in this particular case.

(Jim: Added detailed commit message description)

Closes obsproject/obs-studio#1226

A helper function used with QMetaObject::invokeMethod which allows the
ability to use Qt::DirectConnection if on the Qt UI thread, or
Qt::BlockingQueuedConnection if on another thread to ensure that
regardless of what thread the invokeMethod is called from, that it will
wait until the invoked method has been called.

Instead of manually having to call AddScene each time a scene needs to
be added, use the "source_create" global OBS signal to detect when a
scene has been created, and add the scene to the list automatically.
Allows the ability to add scenes to the main user interface via libobs
API.

Closes obsproject/obs-studio#1226

Due to the ability to track creation of scenes via the "source_created"
global signal, the callback parameter of obs_load_sources has become
somewhat obsolete.  This change allows the ability to pass NULL to the
callback parameter in case the callback is not needed.

Deferred load is used specifically for macOS systems to ensure that Qt
and CEF do not load at the same time.  This causes a slight bit of a
delay in loading the scene after the UI has loaded.  This is not
necessary for other operating systems, so revert to the older load code
in the case of different systems.

Fixes a bug where it would try to save the scene before the scene had
been loaded on macOS.

Prevents a potential crash when being used with audio data that is
unaligned.

Fixes linux-specific compiler error:
libobs/libobs.so.0: undefined reference to `hmax_ps'

Add a new algorithm to calculate the true-peak. It implements the
Whittaker- Shannon interpolation from four samples to create 4
intermediate samples (5 x oversampling) inbetween the middle two
samples.

With 4 samples and 4 intermediate samples the algorithm can be
implemented as a 4x4 vector-matrix cross product, which is ideal for
SSE.

I've also replaced the sample-peak algorithm using SSE as well to
improve performance.

Closes obsproject/obs-studio#1189

win-capture: Avoid obs functions in init_hooks

UI: Fix no_space file naming for replays

rtmp-services: Update ingest list for Restream.io