Improve script_decomp.sh failure handling, among other things

[xNul]

script_decomp.sh changes and context

• Improved failure handling: files that fail any stage of decompilation are copied from script_nxs to a failed folder.
• npktool x script.npk outputs a folder containing files packed within script.npk. These files may have non-NXS file extensions even if they may contain NXS-formatted data (encrypted/compressed NXS data to be accurate) and yet, script_decomp.sh only took the files with the NXS file extension resulting in data loss. I have changed the script to decompile all files in script_nxs instead of only the ones with the NXS file extension.
• Additionally, before this change, two files were not noticed. Once the script.npk is unpacked, there are two files that do not have NXS data inside of them. One is a list of all the NXS files in script.npk and their hierarchy (uncompressed/unencrypted) and the other is a PYC file (only the opcodes are mangled). The PYC file contains Python code for unpacking NPKs.
• Added a progress indicator.

[xforce]

I have merged it for now. But there are still things I would like to change with how the script decompile is done in the future.
Don't like having py2 and py3 mixed. But py2 doesn't handle the chinese strings correctly, so eh.
Also have to somehow figure out why seemingly correct bytecode failes to decompile, probably requires more tweaking of uncompyle6 to handle both of those issues correctly.