(HG2, HG3): use image ID entry names, fix HG2 archive view.

[trigger-segfault]

Change HG2/HG3 archive view entry names to use real ID names.
Fix multiple errors in ArcHG2.cs image view, and add version 0x20 support.

Changes

• Fix bug in ArcHG2.cs where opened images would not pass Version to Hg2MetaData, causing the reader to unpack everything as version 0x10 instead.
• Add support for viewing HG2 version 0x20 as archive, and read real data offset when assigning the HeaderSize field in Hg2MetaData.
• HG2 and HG3 archive image names now use real IDs in names, instead of image index: Aside from HG2 version 0x10, all HG* images contain frame IDs, which are considered part of the name (at least when used in a multi-image fashion).
  • Note: A signed integer is used to match CatSystem 2 behavior. It can handle unnecessarily large and negative frame IDs, and will export frames as a signed number when using the WGC.exe tool (from the devkit).
  • 90% of the time, these IDs will just be the index of the frame. But the other 10%, these IDs are very specifically chosen when working with user interface layers and image variations (like a button highlight state).
  • When used for user interfaces, image IDs usually follow a pattern of reserving the lower decimal digits for image variations, and higher decimal digits for different UI elements (i.e. save/load/title/config button, background, etc.)

Example of new frame ID names:

About new fields referenced

HG3 fields referenced

Frame Header

Type	Value	Description
uint32	OffsetNext	Offset to the next frame
uint32	ID	Identifier for the frame used in game
*	Tags	Image tags, must start with "stdinfo" tag

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HG2 fields referenced

See Version 0x20 fields: ID and OffsetData (referenced for the HeaderSize field assignment)

Frame Metadata: Version 0x10

Type	Value	Description
uint32	Width	Condensed width of the image (without transparency)
uint32	Height	Condensed height of the image (without transparency)
uint32	BitDepth	Number of bits per pixel, 24 or 32 (different usage with version 0x10)
uint32	Reversed1	Unused (would be the slice index, like in HG3)
uint32	Reserved2	Unused (would be the slice length, like in HG3)
uint32	DataSize	Compressed length of Zero Run-length copy data
uint32	OrigDataSize	Decompressed length of Zero Run-length copy data
uint32	CtlSize	Compressed length of Zero Run-length command bits
uint32	OrigCtlSize	Original size of Zero Run-length command bits

Frame Metadata: Version 0x20 (extended)

Type	Value	Description
uint32	OffsetData	Offset (relative to Version 0x20 metadata) to Image Data (Always >= 0x20) Alternatively consider as extra metadata size
uint32	ID	Identifier for the frame used in game
uint32	CanvasWidth	Total width of the image with OffsetX applied
uint32	CanvasHeight	Total height of the image with OffsetY applied
int32	OffsetX	Horizontal offset of the image from the left
int32	OffsetY	Vertical offset of the image from the top
bool32	IsTransparent	True if transparency is used in the image
uint32	OffsetNext	Offset from start of Version 0x10 to next frame Value is 0 if no more frames

Frame Metadata: Version 0x25 (extended)

Type	Value	Description
int32	BaseX	Horizontal center of the image, used for drawing in-game
int32	BaseY	Vertical center of the image, used for drawing in-game