rename file to gUnkClass20.cpp, condense code, and add comments

include/GSfilterModule.h

@@ -0,0 +1,24 @@
+#ifndef POKEREVO_GSFILTERMODULE_H
+#define POKEREVO_GSFILTERMODULE_H
+
+#include "gUnkClass20.h"
+
+struct GSfilterModule
+{
+    u8 unk0[0x10]; // pad
+    u32 unk10;
+    u8 unk14[0x3D8]; // pad
+    gUnkClass20* unk3EC; // pointer to array
+    gUnkClass21* unk3F0;
+    u8 unk3F4[0x18]; // pad
+    u8 unk40C; // counter
+};
+
+extern "C"
+{
+extern GSfilterModule* lbl_8063F410;
+// TODO: member function
+gUnkClass20* func_801FB80C(GSfilterModule*);
+}
+
+#endif //POKEREVO_GSFILTERMODULE_H