Put your copy of Metal Slug 4 here: mslug4h.zip and neogeo.zip from your MAME set
(MAME 0.289's mslug4h), or their files, or the files of the GOG release (its Data\rom folder)
with neogeo.zip.

With the GOG release installed elsewhere, only neogeo.zip goes here: the port finds the install
and takes the Neo Geo system files from this folder.

The files are recognized by their contents, so names and subfolders do not matter.
