GPU: Refactor "VertexShader" namespace to "Shader".

- Also renames "vertex_shader.*" to "shader_interpreter.*"

src/video_core/CMakeLists.txt

@@ -11,8 +11,8 @@ set(SRCS
             pica.cpp
             primitive_assembly.cpp
             rasterizer.cpp
+            shader_interpreter.cpp
             utils.cpp
-            vertex_shader.cpp
             video_core.cpp
             )
 
@@ -35,8 +35,8 @@ set(HEADERS
             primitive_assembly.h
             rasterizer.h
             renderer_base.h
+            shader_interpreter.h
             utils.h
-            vertex_shader.h
             video_core.h
             )