Uses a named mutex to detect if multiple instances of the program are
open, and if so warns the user. When running in portable mode, uses a
separate unique mutex name mapped to the user's config directory to
ensure that no two portable builds use the same config directory. This
way, portable builds do not conflict with normal builds or other
separate portable builds.
OpenGL on Windows is rather unstable and can result in graphical
corruption or the complete inability to start OBS since some GPUs do not
support the minimum requirements after switching to OpenGL. The UI option
is now hidden unless --allow-opengl is passed on the command line.
The D3D adapter is currently unused and we often find users are concerned
when their GPU does not appear in the list.
Instead of checking to see if the window's position is valid, check to
see if the rectangles of the window and the monitor intersect via a
rectangle intersection test.
