Replace debug_print with to_json

to_json and cJSON_Print are now used when displaying debug information.

The main reason for this change it to support sending objects over DAP.

include/plugin.h

@@ -17,12 +17,15 @@
 #ifndef SYSTEM4_PLUGIN_H
 #define SYSTEM4_PLUGIN_H
 
+#include <stdbool.h>
+
+typedef struct cJSON cJSON;
 struct sact_sprite;
 
 struct draw_plugin {
 	const char *name;
 	void (*update)(struct sact_sprite *);
-	void (*debug_print)(struct sact_sprite *, int indent);
+	cJSON *(*to_json)(struct sact_sprite *, bool);
 };
 
 #endif /* SYSTEM4_PLUGIN_H */