TerreateGraphics version 0.8.1

What's Changed

• Improve the function interface. by @uPiscium in #161
• Improve the function interface. by @uPiscium in #162
• Update TerreateCore. by @uPiscium in #163
• develop by @uPiscium in #164
• Remove event systems and update window and joystick event systems. by @uPiscium in #165
• Remove event systems and update window and joystick event systems. by @uPiscium in #166

Full Changelog: v0.8.0...v0.8.1