Huge demos update

-moved C stdlib function definitions to ecs_utils.utils
-added function to calculate mix(linear interpolation) and rsqrt(fast inverse sqrt)
-added some math to vec2 (length, normalize...)
-improved renderer with possibility to use multiple materials (one per block, not perfect solution for parallel compute, but works with some requirements)
-added blending support for material (opaque, additive, mixed)
-added Android support
-added gprahical representation for mouse tools (tool_circle.d)
-added initial support for editing template components variables
-better Component and Templates listing
-added possibility to add/removes components using mouse
-move CLocation to game_core.basic and reuse in every test
-moved tools code from demos to App (now code is fully separated from demos!)
-some improvement and fixes in Snake demo, with additional systems to handle adding and removing entities
-added new demo: Particles. By now demo has several particles to spawn and support for attractors and vortexes (calculation is made as every attractor with every entity)
-fixed bug with window hover and tools
-improved tool behaviour
-added new material
-now window is always opened as maximized windowed mode
-some minor fixes and improvements

demos/utils/source/ecs_utils/math/vector.d

@@ -1,5 +1,7 @@
 module ecs_utils.math.vector;
 
+import ecs_utils.utils;
+
 struct vec2
 {
     this(float v) @nogc nothrow
@@ -71,6 +73,26 @@ struct vec2
         }
         else static assert(0, "Operator "~op~" not implemented");
     }
+
+    float length2()
+    {
+        return x*x + y*y;
+    }
+
+    float length()
+    {
+        return sqrtf(length2);
+    }
+
+    float fastSqrLength()
+    {
+        return rsqrt(length2);
+    }
+
+    vec2 normalize()
+    {
+        return this * fastSqrLength();
+    }
 }
 
 struct vec4