Fixed a bug in listing subdirectories with /maps.

=D silly me... had made a mistake in `/maps` yesterday.

Say your "maps" directory looks like this: `sth.bmp dir1/sth2.bmp`

The output of `/maps` before this commit was:
```
[ImgMap] Contents of the maps directory:
- /sth.bmp
- /sth2.bmp
```
as opposed to its current output:
```
[ImgMap] Contents of the maps directory:
- /sth.bmp
- /dir1/sth2.bmp
```