RottEXPR's Executables Need to Display Error Messages for Missing Required Files

[MasterO2]

@LTCHIPS

RottEXPR's executables should display error messages that specify the files needed to run ROTT.

I saw the thread below made by deus-ex and figured this would be helpful for people having issues getting ROTTEXPR to work:

https://forums.duke4.net/topic/10910-rise-of-the-triad-civvie-11/page__view__findpost__p__356110

Rise of the Triad (Commercial version)

Required files:

SDL2.dll
SDL2_mixer.dll
Rott.exe (commercial)
DARKWAR.WAD (textures, sprites, sounds)
DARKWAR.RTL (singleplayer levels)
REMOTE1.RTS (remote taunt sounds)

Optional files:

DARKWAR.RTC (multiplayer levels)
DEMO1_3.DMO (recorded demo)
DEMO2_3.DMO (recorded demo)
DEMO3_3.DMO (recorded demo)
DEMO4_3.DMO (recorded demo)

Rise of the Triad (Shareware version)

Required files:

SDL2.dll
SDL2_mixer.dll
Rott.exe (shareware)
HUNTBGIN.WAD (textures, sprites, sounds)
HUNTBGIN.RTL (singleplayer levels)
REMOTE1.RTS (remote taunt sounds)

Optional files:

HUNTBGIN.RTC (multiplayer levels)
DEMO1_3.DMO (recorded demo)
DEMO2_3.DMO (recorded demo)
DEMO3_3.DMO (recorded demo)