Fix rotation on render, change rendering code

Premultiply transformation matrix onto vertices before sending onto GPU to
preserve transformation properties of entities before being batched into
a general group. This removes the model matrix from the shader pipeline- instead
in rendering code we deal in world space (which works out to be more intuitive).
Only in the last step in GLSL we convert back to normalised coordinates.

data/shaders/sprite.frag.glsl

@@ -1,6 +1,6 @@
 #version 330 core
-in vec2 texCoord;
 
+in vec2 texCoord;
 out vec4 color;
 
 uniform sampler2D tex;

data/shaders/sprite.vert.glsl

@@ -1,13 +1,11 @@
 #version 330 core
-layout (location = 0) in vec4 data; // (vec2)pos, (vec2)texCoord
+layout(location = 0) in vec4 data; // (vec2)pos, (vec2)texCoord
 
-out vec2 texCoord;
-
-uniform mat4 model;
 uniform mat4 projection;
+out vec2 texCoord;
 
 void main()
 {
-	gl_Position = projection * model * vec4(data.xy, 0.0f, 1.0f);
+	gl_Position = projection * vec4(data.xy, 0.0f, 1.0f);
 	texCoord = data.zw;
 }