GRIM: Avoid compressing LUA-output Savedata

The current LUA code GZips the output from LUA-file I/O that goes to the savegame folder, this makes some of the files rather useless.

* Grim's dialog transcript needs decompressing to be user-readable. Thus it makes little sense to have it stored like that if users want to read outside of ResidualVM.
* efmi.cfg for EFMI is currently stored gzipped, thus hard to edit/read outside of ResidualVM.

This simple fix disables the gzipping of these files, making them user-editable.