make program better to find folder and add fit to screen

[Lars Martin Hambro]

Only way to start this games its to go to download folder with terminal and add files there.

Its not easy to set default folder for find files.

chocolate-doom '-iwad'
                         Chocolate Doom 3.0.1
Z_Init: Init zone memory allocation daemon.
zone memory: 0x7fbc73e77010, 1000000 allocated for zone
Using /home/larsmartin/.local/share/chocolate-doom/ for configuration and saves
V_Init: allocate screens.
M_LoadDefaults: Load system defaults.
saving config in /home/larsmartin/.local/share/chocolate-doom/default.cfg
Game mode indeterminate. No IWAD file was found. Try
specifying one with the '-iwad' command line parameter.

Better to add demo version and add easy way to swich to full version.

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: chocolate-doom 3.0.1-1
Uname: Linux 5.12.0-051200-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu65
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Sat May 1 20:48:23 2021
InstallationDate: Installed on 2019-05-07 (725 days ago)
InstallationMedia: Kubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
SourcePackage: chocolate-doom
UpgradeStatus: Upgraded to hirsute on 2021-04-06 (25 days ago)