Demos update (SpaceInvaders demo)

-added new sprites
-added new functions to vectors
-fixed rendering rotated sprites
-small performance improvement and some bug fixes
-added animations support
-bullets get initial velocity from parent
-added partiles for fire from gun and explosion of enemies

demos/dub.json

@@ -18,6 +18,9 @@
 	"libs-windows-x86_64": ["libs/windows/x64/SDL2","libs/windows/x64/SDL2_Image","libs/windows/x64/cimgui"],
 	"libs-linux-x86_64": ["cimgui","SDL2","SDL2_image"],
 	"lflags-linux-x86_64": ["-rpath=libs/linux/x64/","-Llibs/linux/x64/"],
+	"dflags-ldc" : [
+		"--ffast-math"
+	],
 	"configurations" : [
 		{
 			"name" : "default",