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.

CMakeLists.txt

@@ -6,25 +6,25 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 add_library(blah
-	src/app.cpp
-	src/filesystem.cpp
-	src/common.cpp
-	src/time.cpp
-	src/input.cpp
-	src/stream.cpp
-	src/graphics.cpp
-	src/containers/str.cpp
-	src/drawing/batch.cpp
-	src/drawing/spritefont.cpp
-	src/drawing/subtexture.cpp
-	src/images/aseprite.cpp
-	src/images/font.cpp
-	src/images/image.cpp
-	src/images/packer.cpp
-	src/internal/renderer_opengl.cpp
-	src/internal/renderer_d3d11.cpp
-	src/internal/platform_sdl2.cpp
-	src/internal/platform_win32.cpp
+	src/blah_app.cpp
+	src/blah_filesystem.cpp
+	src/blah_common.cpp
+	src/blah_time.cpp
+	src/blah_input.cpp
+	src/blah_stream.cpp
+	src/blah_graphics.cpp
+	src/blah_string.cpp
+	src/blah_batch.cpp
+	src/blah_spritefont.cpp
+	src/blah_subtexture.cpp
+	src/blah_aseprite.cpp
+	src/blah_font.cpp
+	src/blah_image.cpp
+	src/blah_packer.cpp
+	src/internal/blah_renderer_opengl.cpp
+	src/internal/blah_renderer_d3d11.cpp
+	src/internal/blah_platform_sdl2.cpp
+	src/internal/blah_platform_win32.cpp
 )
 
 target_include_directories(blah