Simplify folder sturcture + String refactor

1) Over time the total amount of files has decreased, and so it made sense to just simplify the folder structure and remove all of the subfolders.
2) Refactor the String class to utilize the existing Vector and StackVector classes instead of managing everything itself.

include/blah_subtexture.h

@@ -0,0 +1,48 @@
+#pragma once
+#include <blah_graphics.h>
+#include <blah_spatial.h>
+
+namespace Blah
+{
+	// Subtexture is a view into a texture, and can be used to 
+	// easily represent sprites in a larger texture atlas.
+	struct Subtexture
+	{
+		// Reference to our Texture
+		TextureRef texture;
+
+		// Source rectangle, in pixels
+		Rectf source;
+
+		// Frame rectangle, in pixels. This describes padding around the image.
+		// This is useful for drawing images that have been trimmed. Ex. if the source
+		// is 32,32, but the original image was 64,64, the frame could be -16,-16,64,64
+		Rectf frame;
+
+		// `draw_coords` are automatically assigned through `update` method
+		Vec2f draw_coords[4];
+
+		// `tex_coords` are automatically assigned through the `update` method
+		Vec2f tex_coords[4];
+
+		Subtexture();
+		Subtexture(const TextureRef& texture);
+		Subtexture(const TextureRef& texture, Rectf source);
+		Subtexture(const TextureRef& texture, Rectf source, Rectf frame);
+
+		// Returns the width of the image
+		float width() const { return frame.w; }
+
+		// Returns the height of the image
+		float height() const { return frame.h; }
+
+		// updates the `draw_coords` and `tex_coords`
+		void update();
+
+		// returns resulting source and frame rectangles based on the provided clip rectangle
+		void crop_info(const Rectf& clip, Rectf* dest_source, Rectf* dest_frame) const;
+
+		// returns a subtexture cropped to the provided rectangle
+		Subtexture crop(const Rectf& clip) const;
+	};
+}