Version 1.6.0

• Added "light" image editing/effects: resize, tint, brightness, contrast and flip (horizontal and vertical)
  • all effects are done live on the GPU
  • when the project is saved a new image with the effects applied is generated
  • device_2D.lua uses this image so that it works with Render2D
  • device_2D.lua also stores which original image + effects were used so that when reloaded in RE Edit, it works as well
  • Watch it in action
• Added a menu entry "File/Delete unused images" to figure out which images (under GUI2D) are used by the project and which ones are not
• Added a performance menu to tweak the frame rate
• Use Alt key to disable most filters (used when selecting images or properties in drop down lists)
• Internally, massive refactoring of the code to use raylib as the backend for ImGui:
  • much more common code between Windows and macOS
  • using custom OpenGL shader (for effects on GPU)
  • generate the panel (using raylib + custom shader) into a texture to be rendered as an image in ImGui