Follow the XDG Base directory specification for storing data like map files

[PureTryOut]

Right now osmin makes 2 folders in my home folder, "Maps" and "osmin", while those should really be located in $XDG_DATA_HOME/osmin (or ~/.local/share/osmin if the $XDG_DATA_HOME environment variable isn't set).

You can read the full specification on where to store any kind of program data/config file here or read a shortened version on the Arch Linux wiki.