- finish CKTexture writer
- add std::enable_if for CKStateChunk::ReadIdent&WriteIdent to limit it in enum type.
- fix error function calling in CKBitmapData writer.
- let CKTexture reader mor formal for mipmap.
- fix CKStateChunk ReadBuffer redirect guideline.
- add a stupid height and width getter for CKBitmapData to serve CKTexture using.
- finish spec fmt image writer and raw bitmap writer.
- fix a possible fatal issue in ReadBuffer(). return nullptr simply rather than allocate a blank buf. otherwise the process of use nullptr to check result will be broken.
- add CanSaveAlpha() method in CKBitmapHandler.
