Added polltimer to input thread.
Updated SettingsWindow
Added retropad.png to assets.qrc
SDLEvents: add a mutex foce event_callbacks
Changed QOpenGLTexture to QSGTexture
Changed QOpenGLTexture to QSGTexture
Removed 'texturenode.h' import
Removed 'texturenode.cpp'
Removed 'texturenode.h'
Updated Core Section
Added retropad icons, along with button icons