Refactor: Extract VertexLoader from command_processor.cpp.

Preparation for a similar concept to Dolphin or PPSSPP. These can be JIT-ed and cached.

src/video_core/CMakeLists.txt

@@ -16,6 +16,7 @@ set(SRCS
             shader/shader_interpreter.cpp
             swrasterizer.cpp
             utils.cpp
+            vertex_loader.cpp
             video_core.cpp
             )
 
@@ -43,6 +44,7 @@ set(HEADERS
             shader/shader_interpreter.h
             swrasterizer.h
             utils.h
+            vertex_loader.h
             video_core.h
             )