Fix PAPA file plugin (#608)

[mirusu400]

Resolved error on PAPA file. (#608) USA version of PAPA file is a bit different between JPN version of PAPA file.

Offset  Size                        Info                    Hex
0x00    ascii                       Magic stamp [PAPA]      50 41 50 41
0x04    0x08                        Unknown                  00 00 00 00 0C 00 00 00  
0x0C    0x04                        Size of header (0)
0x10    0x04                        Count of subfile
0x14    0x04 * (Count of subfile)   Array of *block* offset

(0) Size of header + 0x0B = First block offset


On a block offset..
# on a JPN version
Offset      Size        Info                                            Hex
0x00        0x04        block size
0x04        0x04        0x03                                03 00 00 00
0x08        0x04        Offset of "Msg " flag (Normally Points 0x14)    14 00 00 00
0x0C        0x04        Offset of "Text" (Normally Points 0x18)         18 00 00 00
0x10        0x04        Offset of "Label"
0x[Msg]     ascii       characters "Msg "                               4D 73 67 00
0x[Text]    unicode     Text (Encoding: Unicode) WARN: Text size must be mod by 4.
0x[Label]   ascii       Label (Encoding: Ascii) 

# on a USA version
Offset      Size        Info                                            Hex
0x00        0x04        block size
0x04        0x04        0x03                                03 00 00 00
0x08        0x04        Offset of "Msg " flag (Normally Points 0x14)    14 00 00 00
0x0C        0x04        Offset of "Label" (Normally Points 0x18)         18 00 00 00
0x10        0x04        Offset of "Text"
0x[Msg]     ascii       characters "Msg "                               4D 73 67 00
0x[Label]   ascii       Label (Encoding: Ascii) 
0x[Text]    unicode     Text (Encoding: Unicode) WARN: Text size must be mod by 4.

So, I add simple Messagebox to ask even the PAPA file is JPN version, and read / save differently.

Edit: PAPA file is more complicated than as I think, It seems PAPA file sometimes include not only text file but also archive files. but most scripts are compatible with my plugin.