levels: new E1M3 from Paar

He writes (in readme.txt):
>Notes: I love your work so I thought I could contribute. When I played
>through Ultimate Doom variation of FreeDoom I noticed that map E1M3 was
>largely unfinished. So I began to make my own vanilla version of it. I
>used only resources from shareware episode becase I wanted to be as
>close to the original as possible. The layout is similar and the level
>has an exit to E1M9. I don't know if you'll use it, that depends
>entirely on you. Enjoy!

DW: http://www.doomworld.com/vb/post/1141864 ,
    http://www.doomworld.com/vb/post/1143935 (update)
Signed-off-by: RjY <rjy@users.sourceforge.net>