Extensions, Shaders, Timelines format

EXTN

https://github.com/krzys-h/UndertaleModTool/issues/4#issue-360661852

EXTN: ListChunk
---
<normal FourCC and chunk length in every chunk>

Int32 - Count of (used) extensions
<normal list of 32-bit int pointers to item data, like other ListChunks, using count of used extensions>

Each item:
 32-bit string pointer to empty string: literally "" (just a null terminator), always (hardcoded seemingly)
 32-bit string pointer to extension name (Name)
 32-bit string pointer to class name (ClassName)
 
 List of "extension includes" (files), takes format of List<T>:
  Int32 - Count
  <list of 32-bit pointers to each item, as in List<T> format>
  
  Each item:
   32-bit string pointer to filename (Filename)
   32-bit string pointer to name of function called when game ends, as stored in the extension file, not as referenced in GameMaker, unless they are the same (Final)
   32-bit string pointer to name of function called when extension initializes, as stored in the extension file, not as referenced in GameMaker, unless they are the same (Init)
   Int32 - extension type/kind, value taken directly from project file (Kind)
    0 -> unknown; likely unused
    1 -> DLL
    2 -> GML "placeholder"
    3 -> unknown, but potentially used before GM:S
    4 -> either an included data file, or a "generic placeholder" file
    5 -> JS "placeholder"
    
   List of functions in the include file (if Kind is 2 [which is "GML placeholder"], then this is always empty):
    Int32 - Count
    <list of 32-bit pointers to each item, as in List<T> format>
    
    Each item:
     32-bit string pointer to function name, as referenced in GameMaker (Name)
     Int32 - function ID (Id) - just a unique ID of some kind (very likely based on code analysis, incrementing)
     Int32 - function type/kind (Kind)
      
     Int32 - function return type (ReturnType). Value taken directly from project file:
      1 -> string
      2 -> double
     
     32-bit string pointer to external function name (in the external file); not as it is referenced in GameMaker code, unless they are identical (ExtName)
     
     Int32 - Count of arguments
     Array (NOT a List-type thing) of Int32, count of items is the "Count of arguments" just stated - represents each argument's type. Value taken directly from project file:
      1 -> string
      2 -> double

SHDR

TODO

TMLN

TODO