Break up pokenav into subfiles

The files are separated based on the pokenav resources substruct
ID they use.

include/pokenav.h

@@ -1,6 +1,28 @@
 #ifndef GUARD_POKENAV_H
 #define GUARD_POKENAV_H
 
+typedef u32 (*LoopedTask)(s32 state);
+
+// Return values of LoopedTask functions.
+#define LT_INC_AND_PAUSE 0
+#define LT_INC_AND_CONTINUE 1
+#define LT_PAUSE 2
+#define LT_CONTINUE 3
+#define LT_FINISH 4
+#define LT_SET_STATE(newState) (newState + 5)
+
+// pokenav.c
+extern u32 sub_81C99D4(void);
+
 void CB2_InitPokeNav(void);
+u32 CreateLoopedTask(LoopedTask loopedTask, u32 priority);
+bool32 FuncIsActiveLoopedTask(LoopedTask func);
+void *GetSubstructPtr(u32 index);
+void FreePokenavSubstruct(u32 index);
+void *AllocSubstruct(u32 index, u32 size);
+void Pokenav_AllocAndLoadPalettes(const struct SpritePalette *palettes);
+bool32 IsLoopedTaskActive(u32 taskId);
+
+// pokenav_match_call_ui.c
 
 #endif //GUARD_POKENAV_H