Currently, browser panel is only supported on windows.  So rather than
have to check for _WIN32 in the code everywhere, just move the WIN32
check to cmake, that way we don't have to have _WIN32 checks in the code
everywhere the browser panel code is used, and do not have to remove a
whole bunch of unnecessary _WIN32 #ifdefs for other operating systems
when browser panel support is added for them.

The "Custom" service has been moved, and is now an item called "Custom"
in the "Services" combo box.  This simplifies the stream page of
auto-configuration and removes an unnecessary widget.  Overall a minor
but nice slimline/improvement on user experience.

Add GPL Cooperation Commitment to base directory

obs-filters: Fix unused parameter warnings

Closes obsproject/obs-studio#1602

The GPL is not an EULA and thus it doesn't need to be agreed to.

See also:
https://github.com/HandBrake/HandBrake/pull/1776
https://github.com/videolan/vlc/commit/c07d72146286da935a04be579d6b60bf633cbceb

Closes obsproject/obs-studio#1597

win-capture: Start user-facing monitor count at 1

libobs: Fix scanf type specifiers

frontend-tools: Call modified prop callbacks on script load/reload

This change means that the modified callback for a scripts properties is
always called when first loaded or on a reload. This behavior matches
the properties view for sources, where all modified callbacks are called
when the window opens. This change therefore treats reloading as
equivalent to reopening.

CI: Use modified macOS QT installer

Operating systems don't report monitors from 0, so OBS shouldn't
either. This avoids user confusion when display capture doesn't work.
This does not change monitor count internally.

UI: add a default black background to the PGM output of the multiview

UI: Add support for Restream "Auto" server in auto-config

decklink: Remove redundant const qualifiers

rtmp-services: Remove LiveEdu from services

They now provide ingest URLs on demand in their panel.
The ones in our list point to random OVH IPs that are likely assigned to
new customers by now and refuse the connection on TCP port 1935.

rtmp-services: Update Twitch and Smashcast ingests

Closes obsproject/obs-studio#1544

Twitch Oslo ingest is still omitted as it currently still points to
the Stockholm domain.

obs-filters: Add downward expander filter

The downward expander acts as an advanced gate with smoother effect
since it lowers the level instead of discarding audio when below the
threshold.

The first audio track was not recorded following the API changes for
 custom ffmpeg recording (adding multi-track support).
 This fixes the issue (spotted by EposVox, thanks to him for the report).

The GDI+ based Text Source actually uses Premultiplied Alpha. The edges
of the fonts are therefore incorrectly blended, causing ugly artifacts
especially if bright text above a bright background is used. Here's an
image comparing the new text blending (left) to before (right):
![https://i.imgur.com/VhhkQcZ.png](https://i.imgur.com/VhhkQcZ.png)

Additionally, the game capture has the same problem, so premultiplied
alpha is used there as well now.

Closes obsproject/obs-studio#1613

This patch adds Indian server released by Restream to the list of predefined servers.

Closes obsproject/obs-studio#1626

* UI: Fix mem leak with projectors

* UI: Fix mem leak with ScaleFilteringMenu

* UI: Fix mem leak with sourceProjector

* UI: Fix leak with preview projector in Source menu and Preview

* UI: Fix mem leaks with background color menu

* UI: Fix leak with deinterlace Menu

* UI: Fix leak with scene transition override menu

* UI: Fix leak with scene projector menu

* UI: Fix leak with filter shortcut in Main

* UI: Fix leak with filter shortcut in stats

Authors: Update Contributors list

decklink: Initialize member variable