Move some things around to prepare for multiple pipelines

gpu.h

@@ -28,13 +28,13 @@ typedef struct {
 	VkDeviceMemory depth_img_mem;
 	VkImageView depth_img_view;
 	VkFramebuffer framebuffers[MAX_FRAMES_IN_FLIGHT];
-	VkShaderModule vert_shader;
+	VkShaderModule model_vert_shader;
 	VkShaderModule frag_shader;
 	VkDescriptorSetLayout desc_set_layout;
 	VkDescriptorPool desc_pool;
-	VkPipelineLayout pipeline_layout;
 	VkRenderPass render_pass;
-	VkPipeline pipeline;
+	VkPipelineLayout model_pipeline_layout;
+	VkPipeline model_pipeline;
 	VkCommandPool cmd_pool;
 	VkCommandBuffer cmd_buf;
 	VkFence in_flight;