Added IMGUI_DISABLE compile-time definition to make all headers and sources empty.

imgui_demo.cpp

@@ -65,6 +65,8 @@ Index of this file:
 #endif
 
 #include "imgui.h"
+#ifndef IMGUI_DISABLE
+
 #include <ctype.h>          // toupper
 #include <limits.h>         // INT_MIN, INT_MAX
 #include <math.h>           // sqrtf, powf, cosf, sinf, floorf, ceilf
@@ -4866,3 +4868,5 @@ void ImGui::ShowUserGuide() {}
 void ImGui::ShowStyleEditor(ImGuiStyle*) {}
 
 #endif
+
+#endif // #ifndef IMGUI_DISABLE