[ion/simulator] Don't enable the framebuffer in headless mode

A quick test on a state file with 64k events took 2.5 seconds to process
with the framebuffer vs 1.9 without.

ion/src/simulator/shared/display.cpp

@@ -12,6 +12,7 @@ namespace Display {
 static SDL_Texture * sFramebufferTexture = nullptr;
 
 void init(SDL_Renderer * renderer) {
+  Framebuffer::setActive(true);
   Uint32 texturePixelFormat = SDL_PIXELFORMAT_RGB565;
   assert(sizeof(KDColor) == SDL_BYTESPERPIXEL(texturePixelFormat));
   sFramebufferTexture = SDL_CreateTexture(

ion/src/simulator/shared/framebuffer.cpp

@@ -14,7 +14,7 @@
  * framebuffer to a PNG file. */
 
 static KDColor sPixels[Ion::Display::Width * Ion::Display::Height];
-static bool sFrameBufferActive = true;
+static bool sFrameBufferActive = false;
 
 namespace Ion {
 namespace Display {