Demo update

-added 'dot' function to vector math
-fixed Circle tool rendering
-fixed some potentiall memory leaks
-added 'collision' module which now separates ShootGrid from SpaceInvaders demo
-separate some systems from demos to 'basic' module to better demos functionality sharing
-slow down snake
-added new graphics
-BrickBreaker demo now works (without blocks breaking and with bugged collision detection)

-some bug fixes

demos/source/demos/snake.d

@@ -235,10 +235,10 @@ struct CMovement
     Direction direction;
 }
 
-struct CInput
-{
-    mixin ECS.Component;
-}
+// struct CInput
+// {
+//     mixin ECS.Component;
+// }
 
 struct AppleSystem
 {
@@ -849,7 +849,7 @@ struct CopyLocationSystem
 
 __gshared Snake* snake;
 
-void snakeStart()
+void snakeRegister()
 {
     import game_core.rendering;
 
@@ -890,7 +890,10 @@ void snakeStart()
     launcher.manager.registerSystem!SnakeSystem(101);
 
     launcher.manager.endRegister();
+}
 
+void snakeStart()
+{
     launcher.gui_manager.addComponent(CApple(),"Apple");
     launcher.gui_manager.addComponent(CSnake(),"Snake");
     launcher.gui_manager.addComponent(CParticle(1000),"Particle");
@@ -975,9 +978,9 @@ bool snakeLoop()
     if(launcher.getKeyState(SDL_SCANCODE_SPACE))time += delta_time * 3;
     else time += delta_time;
     
-    while(time > 100)
+    while(time > 200)
     {
-        time -= 100;
+        time -= 200;
         
         launcher.manager.update("fixed");
     }
@@ -992,6 +995,7 @@ bool snakeLoop()
 DemoCallbacks getSnakeDemo()
 {
     DemoCallbacks demo;
+    demo.register = &snakeRegister;
     demo.initialize = &snakeStart;
     demo.deinitialize = &snakeEnd;
     demo.loop = &snakeLoop;