* Checks for OS type before executing
* Checks for Homebrew
* Checks for git (obs-studio build phase)
* Checks for cmake (obs-studio build phase)
* Installs/Updates depdencies
* Installs QT 5.10.1 from bottle (just like obs-studio)
* Pins QT so homebrew does not forcefully update it
* Removed wget dependency, uses macOS' curl
* More output
Following the discussion of #105 the Qt version in the dependency
installation is now hardcoded to version 5.9.2, which is the same as the
main obs version for 20.1.0. Furthermore the names are changed from
osx to MacOS.
